Abstract: An atmospheric NO_x concentration numerical model in response to NO x pollution source was established applying fixed Gaussian model and Thlong program.The average contribution ration of point pollution source,area source and moving source was calculated at each concerned spots,being 17%,17% and 66% respectively.Among the moving sources,urban motor vehicle emission contributed 50 percent,and should be first controlled.Then some options to cut NO_x emission were brought forward,and the improvement results were predicted.The research will provide decision-making support to environmental protection department for NO_x pollution source abatement in Hangzhou.