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In order to study the characteristics and causes of ozone (O₃) pollution in 16 cities of Yunnan Plateau, the methods of COD, backward trajectory and potential source contribution function (PSCF) were used to analyze the O₃ concentrations from 2015 to 2020 of all state-controlled environmental monitoring stations in 16 cities of Yunnan. The results show that the O₃ concentrations in Yunnan gradually increased from 2015 to 2019, and the concentration in 2020 was the lowest due to the COVID-19 pandemic. The peak O₃ concentration appears in spring. The daily change trend is a typical single peak shape, the lowest value appears around 8: 00, and the highest value is between 15:00 and 16:00. High concentrations of O₃ are from the cities of Zhaotong and Kunming in northeastern Yunnan, while low concentrations of O₃ mainly occur in the southwest and northwest border areas. Temperature and relative humidity are two meteorological parameters that have significant effect on O₃ concentration. Temperature has the best correlation with O₃ in winter, and relative humidity has a better correlation with O₃ in autumn and winter than in spring and summer. Finally, source analysis of O₃ showed that local ozone precursor emission sources and long-distance transmission from South and Southeast Asia constituted the major contributions of O₃ in Yunnan.