Legal analysis: It is illegal to exchange Hong Kong dollars privately to earn the difference. According to the Criminal Law of People's Republic of China (PRC), if the circumstances are serious, he shall be sentenced to fixed-term imprisonment of not more than five years or criminal detention, and shall also or only be fined not less than one time but not more than five times the illegal income. It is illegal to set up multiple bank cards in the Mainland, take out Hong Kong dollars in Macau and remit them back to the Mainland to earn the exchange rate difference, because the law clearly stipulates that reselling is not allowed.

Legal basis: Article 45 of the Regulations on Foreign Exchange Control in People's Republic of China (PRC) stipulates that if a large amount of foreign exchange is bought or sold privately, in disguised form or through reselling or illegal introduction, the foreign exchange administration authorities will give a warning, confiscate the illegal income and impose a fine of less than 30% of the illegal amount; If the circumstances are serious, a fine of not less than 30% of the illegal amount but not more than the equivalent value shall be imposed; If a crime is constituted, criminal responsibility shall be investigated according to law.