Objective To explore the effect of the prevention and treatment of unstable bladder after suprapubic prostaectomy by capsaicin instilled into the bladder preoperatively combined with patient-controlled epidural analgesia(PCEA)for benign prostatic hyperplasia(BPH).Methods Sixty patients with BPH underwent suprapubic prostatectomy under epidural anesthesia were randomly divided into control group (30 cases)and treatment group(30 cases),100 ml of 100 μmol/L capsaicin was instilled into the bladder preoperatively for 30 minutes combined with PCEA after operation in treatment group,the control group was only given PCEA.Observed the incidence and continuous time of unstable bladder after operation in two groups.Results Unstable bladder was found in 3 cases of treatment group and they were Ⅰdegree,12 cases happened unstable bladder in control group,3 cases Ⅰdegree,5 cases Ⅱdegree,3 cases Ⅲ degree,1 case Ⅳ degree.There was obvious significance between two groups (P＜0.05).Conclusion Capsaicin instilled into the bladder combined with PCEA can cut off the reflex arc of detrusor contraction more completely and has obvious effect of decrease the incidence of unstable bladder after suprapubic prostatectomy and can be used widely.