Abstract: Based on photochemical formation mechanism of O3 with NOx and VOCs under the solar radiation,pollution characteristic and formation mechanism of O3 were studied at contact area of highway-forest in the Yunnan-Guizhou plateau.The characteristics of atmospheric O3 in Kunming was used to as a comparison,atmospheric O3,NOx and VOCs samples were collected in highway-forest contact area,and temporal and spatial distribution of their concentrations and influence of weather conditions were analyzed.The results showed that the strongest atmospheric photochemical reaction of ozone at contact area of highway-forest had happened in summer ,the concentration of O3 was up to 91.83μg/m3,which was higher than that in other seasons;Positively relationships were found among O3,temperatures and ultraviolet indexes;The formation sensitivity of O3 was closely related to the concentration changing of NO2,which suggested that reducing NOx from vehicles exhaust would be conducive to control the concentration of O3 at contact area of highway-forest.