Under the background of "carbon peaking and carbon neutrality", the carbon emissions produced by the public’s daily consumption cannot be ignored. However, the data show that there is a disunity of knowing and doing in low-carbon consumption. How to get out of the dilemma, and how to guide the public to the low-carbon consumption mode has become an urgent issue to be solved. This study uses the research method of in-depth interview and the grounded theory to build a research model suitable for the analysis of low-carbon consumption behavior, and explains the disunity of knowing and doing. The results show that low-carbon knowledge, personal benefits, moral image and social norms have significant effects on low-carbon consumption behavior, and the mechanisms and paths of their effects are different. On this basis, this study explores and integrates the "knowledge-cognition-behavior" model to analyse low-carbon consumption behaviors, which can provide targeted policy ideas and implementation paths for relevant institutions.