The studying object is urban afforestation in Ningbo city and the main data is color-infrared remote sensing image,which was made in 1998 and its scale is 1∶10000.ArcGIS and ERDAS-based,the eco-environmental effects and the spatial character of the urban afforestation are studied.The results indicate:1) Different situation of afforestation of the road system has differential effects.2) Eco-environmental effect is not balanced in Ningbo city.3) There is correlativity between the relative environment effect and the rate of green coverage in these regions.The relative environment effect will be large,if there is a big coverage rate of green coverage in a particular area.4) The method provides an important index for the evaluation of urban green area and is useful for studying of the green environmental benefit.At the same time,the findings of the study will also provide useful parameters for the design of green systems,especially to design for regions with special demands of green regions,and rationality for urban green community distribution and urban green planning.