The results showed that in the Chinese Han population, the ACE I/D gene polymorphism was associated with the susceptibility of IPF (D vs I: [odds ratio, OR] = 0.53, 95% confidence interval [95%CI] [0.42, 0.67], P < .00001; DD vs II: [OR] = 0.37, 95%CI [0.24, 0.57], P < .00001; DD vs II + ID:[OR] = 0.30, 95%CI [0.21, 0.43], P < .00001), and the angiotensin II (Ang II) level of IPF patients was higher than that of the control group (mean difference [MD] = 14.29, 95%CI [11.20,17.37], P < .00001).The TSA also confirmed that D allele was closely related to the susceptibility of IPF. The gene discussed is AGT; the disease is idiopathic pulmonary fibrosis.