Abstract: There is a huge gap between“Perception” and “Behavior”, and it has become an important issue in exploring how the social psychology factors influence the behavior for source separation. Based on the empirical analysis of the data“Survey on the Living Conditions of Metropolitan Residents” in 2015, this paper analyzed the influencing mechanism of class identification and environmental values on behavior for source separation, examined the mediating effect model of perceived behavior control and perceived behavior motivation, and explored the internal mechanism of promoting behavior for source separation. Through the analysis of the mediating effect model, it is found that class identification has a direct effect on the behavior for source separation, as well as a mediating effect on the behavior for source separation through perceived behavior control and perceived behavior motivation. Environmental values not only have direct effects on behavior for source separation, but also have significant mediating effects on behavior for source separation through perceived behavior control. Therefore, improving the public's green consumption awareness and cultivating the saving habit can enhance the awareness of environmental responsibility and promote the behavior of the public for source separation. Setting up typical and exemplary role models, enhancing class identification and improving environmental satisfaction would play a positive role in promoting the public behavior for voluntary source separation.