Objective To explore the factors influencing nurses′ prevention of suicide in cancer patients. Methods Based on the Theoretical Domains Framework, the descriptive qualitative research method was used to conduct semi-structured interviews with 13 nursing staff. The Theoretical Domains Framework was used as the coding framework, and the relevant theoretical domains affecting nurses′ prevention of suicide behavior in cancer patients were identified by using thematic analysis method. Results The theoretical domains that promoted prevention of suicide by nurses were willingness and social influence, while the theoretical domains that hindered prevention were decision-making process, environment and resources, outcome beliefs and emotions. Conclusion The influencing factors of nurses′ prevention of suicide in cancer patients based on the Theoretical Domains Framework can be used as improvement targets, in a bid to standardize nurses′ prevention of suicide in cancer patients.