[Purposes] Disorderly parking of shared bicycles has become a salient challenge to the development of civilized cities. This study therefore conducts an empirical investigation to reveal the user decision-making mechanism underlying improper shared-bike return behavior. [Methods] Drawing on the Theory of Planned Behavior, this study extends the classical model by incorporating self-identity and moral norms, and develops a cross-sectional questionnaire. A total of 232 valid responses were collect