Objective To investigate the current status of therapeutic relationships,organizational support,and compassion fatigue among psychiatric nurses,and to analyze the mechanism of action between these variables.Methods This was a cross-sectional study.From August to September 2023,totally 310 psychiatric nurses were selected from three Class Ⅲ Grade A psychiatric hospitals in Qingdao,Jinan,and Linyi by convenience sampling.Data were collected using a general information questionnaire,the Therapeutic Relationship Assessment Scale-Nurse(TRAS-N),the Perceived Organizational Support Scale(POSS),and the Chinese version of Compassion Fatigue short Scale(CCFS).SPSS 22.0 and the Process macro plugin were used for data analysis.Results A total of 310 questionnaires were distributed,with 282 valid responses,yielding a response rate of 90.97%.The total score for TRAS-N among the 282 psychiatric nurses was(95.59±18.75),the total score for CCFS was 45.50(24.75,68.25),and the total score for POSS was(43.66±13.34).Therapeutic relationships were positively correlated with organizational support and negatively correlated with compassion fatigue,while organizational support was negatively correlated with compassion fatigue(all P<0.01).Organizational support had a direct positive effect on therapeutic relationships(β=0.291,P<0.01)and also had an indirect effect through the mediating effect of compassion fatigue(β=0.212,P<0.01),with the mediation effect accounting for 42.15%of the total effect.Conclusions Compassion fatigue partially mediates the relationship between organizational support and therapeutic relationships in psychiatric nurses.Nursing managers should enhance organizational support for psychiatric nurses to reduce their levels of compassion fatigue,thereby improving therapeutic relationships.