Objective To assess the occupational health risks of chemical hazards in the workplace of a phthalic anhydride production enterprise in Tongling, and to explore the application of three occupational health risk assessment Methods. Methods The results of chemical harmful factors and occupational health survey in a phthalic anhydride production enterprise in Tongling were collected. The occupational health risk assessment was carried out by three Methods:contact ratio method, contact index method and comprehensive index method. Results The concentration of naphthalene in oxidation inspection posts was 15.4 mg/m³, and that in phthalic anhydride packaging and product loading posts was 0.19 mg/m³, which was a middle-risk post of occupational health. The Kendall'Tb coefficients of the three methods were 0.632, 0.447 and 0.707, respectively. There was no significant difference (P> 0.05), and the consistency was good. Conclusion The three methods can objectively assess the occupational health risk of chemical hazards in the workplace, and the comprehensive index method should be given priority. It is of great significance to guide enterprises to take measures to control occupational hazards and reduce occupational health risks.