From September 1991 to July 1997, Yan Fengying was engaged in drug development, research and testing at the Scientific Research and Technology Center of Tianjin Traditional Chinese Medicine Group Co., Ltd., and participated in the "Eighth Five-Year Plan" national key research projects on traditional Chinese medicine. , which provides a scientific basis for the determination of the active ingredients of Chinese traditional Chinese medicine, the formulation of quality standards, the establishment of testing methods and clinical medication. This project won the “First Prize for Scientific and Technological Progress Award” from the State Administration of Traditional Chinese Medicine in 1996 and the “Third Prize for National Scientific and Technological Progress Award” in 1997. In August 1997, Yan Fengying was assigned by the organization to Tianjin Hualida Bioengineering Company, the first bioengineering pharmaceutical company with intellectual property rights in China, as the person in charge of corporate technical quality management. She led the company's technical backbone to successfully complete product quality research. The production, technical quality and management standards she presided over have become important references for national standards and laid a quality foundation for products to enter the international market. Subsequently, Yan Fengying took over the important task of market development. When the market for similar products at home and abroad is almost fierce, she put forward the marketing concept of "driving the market through academic promotion". According to the China Central Television website, after three years of hard work, the annual sales of Hualida products increased from 100,000 to 1.7 million, with annual revenue of hundreds of millions of yuan. From a sluggish enterprise to one of the city's per capita Ranked among the enterprises with the highest profits and taxes, it has become a model for the leapfrog development of high-tech enterprises in the city.

In 2000, in order to accelerate the construction of China's own umbilical cord blood stem cell bank, preserve China's precious national resources, promote the transformation of stem cell transplantation technology, gene therapy technology and drug research results into real productivity, and provide more patients with To provide a hope of life, Yan Fengying still gave up the honor, status, and benefits she had gained after years of hard work, and joined the ranks of pioneers in stem cell industrialization. In just three years, it has stored more than 30,000 stem cells, becoming one of the largest and most advanced cord blood stem cell banks in the world. Some indicators have reached or exceeded international standards, and dozens of stem cells have been provided to patients, 70% of which The patient's transplant was successful, saving endangered lives. After ten months, Yan Fengying compiled the "standard operating procedures" for China's first umbilical cord blood stem cell bank, with a total of 13 volumes and 230,000 words. Tianjin Cord Blood Bank has successfully held several international stem cell academic forums. After visiting the Tianjin National Stem Cell Industrialization Base, many domestic and foreign experts and colleagues unanimously praised it as world-class and China's stem cell industrialization is at the forefront of the world.

In July 2001, Yan Fengying joined the "National Stem Cell Product Industrialization Base" demonstration project. Three months later, she presided over the formulation of the standard operating procedures for China's first umbilical cord blood stem cell bank and participated successively. He has participated in projects such as "Construction of Umbilical Cord Blood Hematopoietic Stem Cell Bank and Related Technology Research" and "Hematopoietic Stem Cell Biology and Cell Engineering", and presided over the "Study on the Effect of Orally Attenuated Salmonella Carrying Human PF4 Gene on Hematopoietic Reconstruction in Mice with High-dose Chemotherapy" and other projects. In order to let more people understand what stem cell technology is and what the role of umbilical cord blood storage is, Yan Fengying traveled around to explain it to people. While working as a business manager, she also continued her research work. Every Thursday, Yan Fengying walks into the laboratory.

In 2004, national leader Zeng Qinghong visited the base to inspect and provide guidance and highly affirmed their work. Kelly lives in a family in New Mexico, USA. In March 2001, Kelly was diagnosed with aplastic anemia, which was severe. In order to save their daughter from the disease and save her life, her adoptive parents Linda and his wife tried every means to treat her. Linda and his wife knew that the dawn of little Kelly's life was in her hometown of China, because Kelly was a child they adopted from China. In February 2003, Linda came to China with high hopes and searched for matching stem cells for her Chinese adopted daughter Kelly through the Red Cross branches in the Chinese Bone Marrow Stem Cell Bank. Because little Kaili was an abandoned baby adopted in a welfare home, and her parents and siblings could not be found, we had to find an unrelated stem cell provider for her, and the one she found might only be 1 in 50,000. 1 in 100,000. In October 2003, Little Kelly's condition deteriorated again, and Linda came to China for the second time. As soon as Yan Fengying saw the report that Linda came to China again to find stem cells for her daughter, she immediately notified Xiehe Company's branch in Hunan to get in touch with Linda. Xiao Kaili's information was quickly sent back to Tianjin. To perform allogeneic stem cell transplantation, both parties are required to have at least 4 matching sites. The more matching sites, the greater the certainty. Four loci were matched, and five were also matched. They continued to search until a magical moment - I couldn't believe it, there was actually a stored cord blood that matched all six loci of little Kaili. Lin Da was very excited after visiting the stem cell bank, and Yan Fengying's doubts about China's stem cell technology were all wiped away.

In order to repay the society and provide some love to the children who have lost their loved ones, Yan Fengying adopted five school children in Tianjin’s “Sunshine Project” to provide love to children from single-parent impoverished families and be their “love” "Mom" uses her own salary to support her children's studies every year until they complete their studies.