Objective To understand the status of quality control in occupational medical examination (OME) institutions in Guizhou Province. Methods A total of 124 registered OME institutions actively conducting OME in Guizhou Province were selected as the study subjects using the judgment sampling method. The evaluation was conducted by on-site document reviews, practical skill assessments, and investigation of OME practices for quality evaluation and analyzing their quality control performance. Results The public institutions accounted for 71.0% with a 41.5% of OME workload, while private institutions accounted for 29.0% with a 58.5% of OME workload among these 124 OME institutions. The overall pass rate for quality evaluation of OME institutions was 16.9% (21/124), with a total of 1 296 items failed to pass the quality evaluation. Among the unqualified items, organizational structure, quality control management systems, OME quality control, and information reporting accounted for 15.2%, 21.7%, 52.8%, and 10.3%, respectively. The unqualified rate of quality assessment items of OME institutions was 24.5% (1 296/5 288), and the unqualified rate was lower in public institutions compared with private institutions (22.4% vs 29.3%, P<0.01). The rates of the three key unqualified items, including chest radiography conclusion evaluation, audiogram calculation and conclusion evaluation, and blood lead comparison were 9.8%, 74.8% and 71.4%, respectively. The rates of unqualified audiometry operation test and chief physician theory test were 74.8% and 9.7%, respectively. Conclusion The quality of OME institutions in Guizhou Province requires continuous improvement, particularly in enhancing the abilities of audiometry operation, calculating audiogram results and conducing right conclusion, and blood lead inter-laboratory comparision.