Urban household waste causes serious pollution of the urban ecological environment. Waste separation and processing is an effective approach to reduce the ecological environment damage caused by household waste. From the perspective of the source of urban household waste separation, this paper investigates the influencing factors of the willingness of urban residents to separate household waste based on the theory of planned behavior. Through regression analysis, it was found that: Firstly, waste separation attitude, waste separation cognition, subjective norm, perceived behavioral control, and situational factors have significant positive impacts on the willingness of urban residents to separate waste, and the degrees of these impacts show a decreasing order; Secondly, the willingness to separate waste has a significant positive impact on the implementation of urban residents’ actions to separate waste.