With the acceleration of urbanization, environmental problems are becoming more and more critical. As an important subsystem of urban environment, urban forest offers many kinds of ecological services which benefit the city dwellers. The assessment of urban forest ecological services can improve the construction of urban forest effectively and guild strategic decisions, so that urban forest's ecological services can be maximized. This paper clarified the concepts of urban forest and the connotation of urban forest ecological service values, and compared and analysed different methods. Based on the development of urban forest ecological services, this paper concluded the approaches of urban forest ecological services into three categories: economic valuation of single trees, comprehensive valuation of ecological services, and spatially explicit landscape model valuation. Finally, the shortness of current urban forest ecological services evaluation methods and its prospects were concluded to enrich the theory of urban forest ecological services valuation, and to direct the planning of urban forest.