In order to formulate O3 pollution control policies and reduce O3 pollution in Xinzhou City, the monitoring data of the air quality in Xinzhou in 2018 from the national control station was used to simulate the formation and analyze the sources of O3 pollution, using WRF-Smoke-CAMx model, OSAT module and CPA module. The results indicate that O3 pollution is serious from May to August in the whole year. The number of days when O3 becomes the primary pollutant is 109, which accounts for 36%. The monthly average concentration of O3 shows a single-peaked curve, and the concentration of O3 on weekends is higher than that on weekdays. The contribution rate of extraneous O3 and its precursors to the total O3 concentration in Xinzhou City is 8.86%~35.31%, while the contribution rate of mobile sources is 9.65%~25.68%. Among all the industrial sources, the production and supply of power and heat industry has the largest contribution rate which is 28.25%. The formation of O3 was controlled by NOX in most areas of Xinzhou City, while by VOCs in a few areas of Xinfu District, Yuanping City and Dingxiang County, which accounts for 0.86% of the area of Xinzhou City. Reducing the emission of VOCs or NOX separately can not significantly decrease the concentration of O3. When the emission of VOCs and NOX are reduced simultaneously, it reaches better performance by keeping the reduction ratio of NOX higher than that of VOCs.