It is important to solve the problem of the national energy shortage and improve the urban ecological environment by promoting waste sort to break out of encirclement with waste, reduce greenhouse gas emissions and slow down global warming process. Based on 2 036 respondents field survey data from 6 districts of Ningbo City,this paper analyzes the influencing factors of willingness and behavior on waste sorting, and forward waste sorting mechanism of urban residents. The results show as follows: there are differences between willingness and behavior on waste sorting, that the proportion of sorting willingness (82.5%) is significantly higher than the actual behavior' s (13%), and it means that higher waste sorting willingness doesn' t necessarily result in higher behaviors. Willingness and behaviors on waste sorting can be influenced by different factors. Sorting behaviors much depend on situational factors, the cognition and attitude, while sorting willingness is mainly affected by the cognition and attitude, personal feature and promoting measures. There are many factors influencing the willingness and behaviors and their relative essentialities are different. Behavior of waste sort is more affected by situational factors (namely convenience),whereas willingness to sort has greater impact to personal feature, and the cognition and attitude are important for both. The pilot waste sorting has greater impact on behavior than willingness. The former is significantly influenced, while the latter is not. Conclusively, in terms of the outcomes of empirical analysis, some special suggestions are put forward to further improve the waste sorting in China: Firstly,it reminds us that the convenience of facilities of waste sorting is still the most important factor, so the related facilities and service supply system need to be perfected. Secondly, the willingness to waste sorting needs to be strengthened by spreading the sorting knowledge,and fostering a sense of personal responsibility and values to waste sorting. Thirdly,to establish associated mechanism of short-term incentives and long-term incentives,and combine with the internal and external condition,are promoting the formation and maintenance of behavior of waste sorting.