ObjectiveGuided by the ecosystem theory model framework, we aimed to explore the influence of three ecological dimensions (social, family and psychological factors) on suicidal intention in people with severe mental illness (SMI). We hypothesized that three factors influence suicidal intention, and that psychological factors may play a mediating role in the influence of social and family factors on suicidal intention.MethodsWe collected 994 patients with SMI aged 18 and above from May 2021 to March 2022 in the Fourth Hospital of Fuzhou City. We used logistic regression to analyse the association between social, family, psychological factors and suicidal intention. Furthermore, we explored the mediating effects among the influencing factors.ResultsYounger male patients with schizophrenia were more likely to have suicidal intention due to psychosocial family factors (p < .05). Social factors (poor interpersonal relations, social retreat, social activities outside the home), family factors (parental functions, activities within the family, family functions), psychological factors (anxiety, depression, interest in the outside world, overt aggression, lack of accountability and planning) were all independent risk factors for suicidal intention in patients. Mediation analysis showed anxiety and depression mediated the role of social and family factors on suicidal intention (p < .05).ConclusionSocial, family and psychological factors were important risk factors for suicidal intention, with anxiety and depression being partial mediators for suicidal intention. Therefore, interventions that enhance family and social functioning and reduce anxiety and depression may be effective in reducing suicidal intention in SMI.