Objective. To investigate the diagnostic and staging value of serum angiotensin-converting enzyme (sACE) in sarcoidosis. Methods. Patients with suspected sarcoidosis treated in the Department of Pulmonary and Critical Care Medicine of the China-Japan Friendship Hospital from 2010 to 2020 were included. The data of sACE, erythrocyte sedimentation rate (ESR), complete blood count (CBC), lung function, bronchoalveolar lavage, and biopsy were collected. The differences between the sarcoidosis group and the nonsarcoidosis group and between different stages of sarcoidosis were compared. The receiver operating characteristic (ROC) curve analysis was used for the diagnostic test of sACE in sarcoidosis. Results. A total of 84 cases with suspected sarcoidosis were included, among which 70 cases were confirmed to be sarcoidosis by biopsy. The mean value of sACE in sarcoidosis patients was 56.61 +/- 30.80 U/L, which was significantly higher than that in nonsarcoidosis patients (28.07 +/- 14.11 U/L, P=0.001). The level of sACE in sarcoidosis patients with peripheral superficial lymph nodes and multiple system involvement was significantly higher than that in intrathoracic sarcoidosis patients (P=0.009); the percentage of lymphocytes in bronchoalveolar lavage fluid (BALF) of sarcoidosis patients was 45.39 +/- 22.87%, which was significantly higher than that of nonsarcoidosis patients (P < 0.001). There was no correlation between sACE and ESR (correlation coefficient=-0.167). According to ROC curve analysis, when sACE +/- 44.0 U/L, the sensitivity of sarcoidosis diagnosis was 61.4%, the specificity was 92.9%, and the AUC was 0.819. Conclusion. sACE has a good specificity in the diagnosis of sarcoidosis. sACE values in patients with sarcoidosis with systemic involvement were higher than those with simple intrathoracic sarcoidosis.