Folic acid, as a one-carbon unit transferase coenzyme, participates in the synthesis of purine and thymine, and is an important element of the nervous system. Vitamin B12 participates in methyl conversion and folate metabolism in the body, promoting the conversion of 5-methyltetrahydrofolate to tetrahydrofolate. It has been reported that the lack of serum folic acid and B12 is associated with an increased risk of cognitive impairment. The explanation mechanism of the relationship between folic acid deficiency and cognitive dysfunction may be that folic acid deficiency leads to impaired central nervous system methylation, resulting in insufficient methyl synthesis of myelin sheaths, neurotransmitters, membrane phospholipids and deoxyribonucleic acid. Our previous studies showed that preoperative folic acid supplementation can alleviate myelin damage and cognitive impairment in young rats caused by sevoflurane anesthesia. Therefore, this study further explored the preoperative folic acid and coenzyme B12 supplementation for children's delirium and long-term neurobehavioral changes after general anesthesia.