It is not illegal, but it is illegal to buy and sell mercury privately. According to relevant information, it is definitely illegal to buy and sell mercury without approval. Buying and selling mercury requires both the buyer and the seller to obtain a hazardous chemicals business license. If you buy and sell privately, it will seriously disrupt social order, and you may be suspected of illegal business operations and need to bear certain criminal responsibilities. Article 225 of the Criminal Law of People's Republic of China (PRC): Whoever, in violation of state regulations, commits one of the following illegal business operations and disrupts the market order, if the circumstances are serious, shall be sentenced to fixed-term imprisonment of not more than five years or criminal detention, and shall also, or shall only, be fined not less than one time but not more than five times the illegal income; If the circumstances are especially serious, he shall be sentenced to fixed-term imprisonment of not less than five years, and shall also be fined not less than one time but not more than five times for illegal gains or confiscation of property:

1. Without permission, engaging in franchise or monopoly commodities or other commodities whose operation is restricted by laws and administrative regulations;

2. Buying and selling import and export licenses, import and export certificates of origin and other business licenses or approval documents stipulated by laws and administrative regulations;

3, without the approval of the relevant competent departments of the state, illegally engaged in securities, futures, insurance business, or illegally engaged in fund payment and settlement business;

4. Other illegal business operations that seriously disrupt the market order.