Abstract: Based on the multi-objective regional geochemical survey, the nitrogen reserves in surface soil (0-20 cm) in Harbin-Suihua area are calculated, with comparison of soil nitrogen density between different ecosystems and different soil types. The variation characteristics of soil nitrogen storage in the last 20 years are studied. The result shows a slightly increase of soil nitrogen storage during this period, which is caused by the remarkable effects of wetland and forest ecosystem on soil nitrogen fixation.