Background: Currently, many detection methods have high sensitivity to the diagnosis of lung cancer. However, some postoperative patients with pulmonary nodule were eventually diagnosed as benign nodules. The ideal evaluation of an individual with a pulmonary nodule would expedite therapy for a malignant nodule and minimize testing for those with a benign nodule.Methods: This case-control study is designed to explore the relationship between ACE1 rs4646994 polymorphism and the risk of lung cancer in patients with pulmonary nodules, 400 individuals with lung cancer and benign pulmonary nodules were included. A DNA extraction kit was used to extract plasm DNA from peripheral blood. The relationship between ACE1 rs4646994 and the risk of lung cancer in patients with pulmonary nodules was determined by chi-square test, logistic regression analysis and cross analysis. Results: The results showed that the DD genotype of ACE1 rs4646994 may increase the risk of lung cancer in patients with pulmonary nodules, and this correlation was more significant in the female subgroup. In the age stratification analysis, it was found that the risk of lung cancer was significantly increased in the DD genotype of ACE1 rs4646994 in the older subgroup (> 45 years). In addition, the possibility of EGFR mutation in lung adenocarcinoma patients with ACE1 rs4646994 DD genotype was lower than that of II or ID genotype carriers. Conclusions: Our study indicated that ACE1 rs4646994 polymorphism increases the risk of lung cancer in patients with pulmonary nodules from China.