Pyrimethamine is a broad-spectrum veterinary drug widely used for antigen insects. In addition, pyrimethamine is also used in aquaculture, which can enhance the disease resistance of aquatic fish. However, the side effects of pyrimethamine are serious, excessive use can damage the reproductive system of livestock and poultry, and is not easy to recover. Pyrimethamine can inhibit the primary infrared phase of some falciparum malaria and vivax malaria, so it is a better preventive drug. Although it has no obvious effect on the gametophyte of Plasmodium, the development of Gametophyte in mosquitoes can be affected after the blood containing the drug enters the mosquitoes, so the transmission can be blocked. The principle of action is to inhibit dihydrofolate reductase, affect the utilization of tetrahydrofolate, reduce the synthesis of nucleic acid and inhibit the reproduction of Plasmodium. At the same time, pyrimidine and chloroquine can protect the placental pathological changes after malaria infection by reducing the levels of oxidative stress and apoptosis, and can also effectively reduce the proportion of infected red blood cells in the blood, so as to achieve a good effect of malaria treatment. Moreover, it has enrichment effect in aquatic products, beyond a certain range, it will cause hemolytic anemia after human consumption, and even has direct toxicity to the central nervous system.