By using the monthly surface ozone data collected at remote sites over East Asia(EA) and related wind field and precipitation data,this paper studies the ozone seasonal cycle,interannual variation characteristics and their relations to EA monsoon,and the main factors influencing the surface ozone.The results show that the spring maximum and summer minimum of surface ozone occurs widely across mid-latitudes in the North Hemisphere at remote sites,including most parts of EA.However,the surface ozone has a summer maximum in the region of 33-43°N over EA,and a later winter/early spring maximum in south of 20°N over EA.These ozone seasonal cycle features were mainly controlled by the seasonal transitions of East Asia winter/summer monsoon circulations.The latitudinal differences of appearing time of surface ozone peaks in spring over EA Pacific Rim regions are closely related to the differences of pollutants transport path and strength from Asian continental.The analysis of seasonal variations of potential vorticity,upper air jet stream around tropopause,and the variation of vertical circulations shows that the winter and spring are the strongest periods of air mass transport from stratosphere to troposphere.However,the transport from stratosphere to troposphere is weakest from May to November and has lower impact on surface ozone.The interannual variations of EA summer monsoon onset(time and strength) and patterns of circulation are the main reasons of surface ozone interannual variations in spring and summer over EA Pacific Rim regions.The other factors for surface ozone variation could be attributed to monsoon precipitations,cloud effects on photochemistry and the stratosphere-troposphere transport.