Abstract: 　Objective　To explore the gene mutation spectrum of 21 hydroxylase deficiency (21-OHD) with I2G gene mutation in children, and to analyze the relationship between genotypes and clinical phenotypes. Method　The clinical data of 21-OHD children with I2G gene mutation during 2009-2016 were collected, and the relationship between genotypes and clinical phenotypes was analyzed. Results　In 26 cases (20 males and 5 females), there were 22 cases (84.62%) of salt wasting patients (SW) and 4 cases (15.38%) of simple virilization patients (SV). There were 16 cases of I2G homozygous mutation (61.5%), in which, except that one patient was SV, the other 15 patients all showed SW. There were 10 cases of complex heterozygosity mutation (38.5%), of which 7 cases were SW, carrying p.Q319X, p.R357W, p.R484P, p.V282L, Gll0fs, ClusterE6 mutation respectively. One SV girl carried p.I172N mutation gene. The other 2 SV boys (sibling Brothers) carried p.Q319X mutation gene and there were repeats on paternal allele while there was I2G heterozygous mutation on the maternal allele. Conclusion　The genotype of 21-OHD children with I2G mutation is in good agreement with clinical phenotype, and mostly homozygous mutation is SW. The clinical manifestation of compound heterozygous mutation is mainly determined by the mutant gene with less damage of enzyme activity.