Aim To study the incidence of the insertion/deletion (I/D) polymorphism of angiotensin converting enzyme (ACE) gene in She population and investigate the association between polymorphism of ACE gene and carotid intima-media thickness (IMT). Methods The polymorphism of ACE gene was genotyed by polymerase chain reaction (PCR) in 200 She population and 224 Han population. The sample was characterized for relevant clinical and biochemical parameters. Carotid IMT was measured by quality intima-media thickness (QIMT). Association of genotype and allele frequencies with carotid IMT were analyzed. Results The frequency of ACE gene polymorphism was consistent with Hardy-Weinberg law. ACE II genotype frequency and carotid IMT in She population were 0.365 and 510±113 μm, ID genotype frequency and carotid IMT in She population were 0.465 and 544±129 μm, DD genotype frequency and carotid IMT in She population were 0.17 and 584±181 μm. ACE II genotype frequency and carotid IMT in Han population were 0.540 and 528±139 μm, ID genotype frequency and carotid IMT in Han population were 0.371 and 554±182 μm, DD genotype frequency and carotid IMT in Han population were 0.089 and 591±218 μm. The frequency of ACE gene polymorphism had significant difference between the two races. There were variabilities in the three genotypes of carotid IMT.Conclusion The polymorphism of ACE gene had ethnic differences, and the thickening of carotid IMT was significantly relevant to the three genotypes of ACE.