Objective To explore the moderating role of nurses′ medication safety competence on the relationship between medication environment and unsafe medication behaviors. Methods Totally, 303 registered nurses were selected by convenient sampling. They were asked to fill out the general information questionnaire, the Nurses′ Perception of Medication Environment Scale, Medication Safety Competence Scale and Nurses′ Medication Unsafe Behavior Scale. Results The nurses scored a median of 105.44 (IQR:88.41-118.01) points in medication safety competence, 100.00(IQR:93.00-106.00) points in medication environment, and 12.00 (IQR:9.00-18.00) points in unsafe medication behaviors. Medication environment (β=-0.331, P<0.05) and medication safety competence (β=-0.251, P<0.05) could negatively predict nurses′ unsafe medication behaviors. Nurses′ medication safety competence played a moderating role between medication environment and unsafe medication behaviors (β=0.216, P<0.05), and the boundary value of moderating effect was 123 points. Conclusion Medication environment and medication safety competence have a direct effect on nurses′ unsafe medication behaviors. Nurses′ higher competence of medication safety can buffer the adverse effects of medication environment on their unsafe medication behaviors, thus reducing their unsafe medication behaviors.