N-acetyl transferase 2 is an important Ⅱ metabolic enzymes in human bodies, it plays an important role in metabolism of aromatic amine and the hydrazine. NAT2 gene is given priority to fast acetylated gene phenotypes in Our country, the most common genotype are NAT2*4A, NAT2*6A, NAT2*7B. The Slow NAT2 genotypes with isoniazid acetylated metabolism is related to the drug-induced hepatitis, differences of NAT2*5 in allele frequency is one of the main reasons that cause slow frequency of acetylated for the differences. Research of NAT2 gene polymorphisms has important significance in isoniazid individualized treatment and reducing or mitigating adverse drug reaction.