A Weather Research and Forecasting model， and Ozone Source Apportionment Model of Nested Air Quality Prediction Model System（WRF-NAQPMS/OSAM） was used to simulate an ozone pollution in Zhongshan during September 2019， and the source of ozone is analyzed. The simulations showed reasonable agreement with the observations. The regional transport contributed significantly to the ozone concentration in Zhongshan， the average contribution ratio was 82.9%，the average local contribution ratio was 17.1%， solvent usage and vehicle emissions contributed the most to ozone in Zhongshan， with an average contribution rate of 43.0% and 42.7% respectively. The contribution of industrial sources cannot be ignored， with an average contribution of 11.0%. It indicated that ozone formation in Zhongshan was dominated by VOCs.Solvent usage， vehicle emissions and industrial emissions of toluene， m/p-xylene， o-xylene，1，2，3-trimethylbenzene， n-butane and isopentane played a leading role in the O₃ formation in Zhongshan which were important precursors for ozone pollution control. It is suggested that a long term ozone prevention and control strategy be established， which is dominated by VOCs control as well as VOCs and NO_X coordinated control.