Objective To explore the current status of rumination in inpatients with metastatic prostate cancer(mPCa)under the disease coping mechanism,and analyzing its influencing factors.Methods From March 2021 to December 2022,267 mPCa inpatients at the Tenth People's Hospital of Tongji University were selected as the study subject using convenience sampling.The survey was conducted using the General Information Questionnaire,Chinese Version of Event Relate Rumination Inventory(C-ERI),Medical Coping Modes Questionnaire(MCMQ),International Prostate Symptom Score(IPSS),and Social Support Revalued Scale(SSRS),and the factors influencing the rumination in patients were analyzed.Results This study collected 260 valid questionnaires,with an effective response rate of 97.4%(260/267).The total score of rumination in 260 mPCa patients was(31.08±6.46),with invasive rumination and purposeful rumination scores of(14.13±4.44)and(16.95±4.55),respectively.The initial prostate-specific antigen index,confrontation medical coping modes were the influencing factors of invasive rumination in mPCa patients(P<0.05).The initial prostate-specific antigen index,course of disease,social support,and confrontation medical coping style were the influencing factors of purposeful rumination in mPCa patients(P<0.05).Conclusions The rumination of mPCa patients is above the medium level,and is influenced by multiple factors under the disease coping mechanism.Clinical medical and nursing staff should combine the clinical situation and characteristics of mPCa patients,provide personalized interventions as early as possible,and assist patients in improving their positive cognitive processing abilities.