Objective To investigate suicidal ideation among patients with lung cancer, and to explore the influence of connectedness, psychological pain and hopelessness on suicidal ideation, so as to provide reference for developing targeted intervention. Methods A total of 366 lung cancer patients were surveyed using the Patient Health Questionnaires, the Connectedness Scale, the Psychache Scale and Beck Hopeless Scale, and the structural equation modeling was utilized to analyze the relationships among these variables. Results The incidence of suicidal ideation among lung cancer patients was 22.68%. Connectedness, psychological pain and hopelessness could directly affect suicidal ideation (direct effect was 0.13, 0.37 and 0.17), while connectedness indirectly affected suicidal ideation through psychological pain and hopelessness (indirect effect was 0.38), its total effect value was the largest(0.51), and it could adjust the effect of the hopelessness on suicidal ideation. Hopelessness indirectly affected suicidal ideation through psychological pain (indirect effect was 0.17), and there was no interaction between them. Conclusion The incidence of suicidal ideation among lung cancer patients is high. It is significant to reduce the incidence of suicidal ideation via taking enhancing patients′ sense of connection as the core, reducing their psychological pain and increasing their hope.