Abstract: Based on the ozone monitoring date, the spatio-temporal variation of ozone concentration and its influencing factors of 35 cities in Northeast China from 2015 to 2018 were analyzed via spatial auto-correlation analysis and geographical detector. The results show that the interannual variation of ozone concentration increased from 2015 to 2018 and the monthly ozone concentration followed a pattern of inverted "V", which was higher in spring and summer and lower in autumn and winter. The high ozone concentration areas were mainly distributed in Liaoning Province and Jilin Province, which expanded to the north due to the effect of temperature. The ozone concentration had significant characteristics of agglomeration with hot spots distributed mainly in Liaoning Province. Meteorological factors and socio-economic factors all had significant effects on the distribution of ozone concentration. Temperature, the proportion of secondary industry and the ownership of civilian automobiles were all significantly correlated with ozone concentration.