First, open the national government service platform applet, select the epidemic prevention health information code service, and display the code on this page after receiving the epidemic code. "Multi-code" refers to the electronic health code (including COVID-19 vaccination information), communication big data travel card, and self-inspection information of peer unannounced visitors. It is a personal two-dimensional code (certificate) based on personal real data, which is generated by self-service online declaration and comparison with epidemic prevention big data information. It is also electronic certificate where individuals travel daily during the epidemic prevention and control period.