Purpose: This study aimed to evaluate the changes of patients' quality of life (QoL) after cystoprostatectomy as a treatment for locally advanced prostate cancer (LAPC) with the bladder invasion and to determine risk factors for postoperative poor QoL. Materials and methods: Between Jan 2012 and December 2015, 27 patients who received cystoprostatectomy for LAPC with the bladder invasion were retrospectively included. QoL was assessed with the functional assessment of cancer therapy-prostate (FACT-P) questionnaire scores. Determinants for postoperative poor QoL were investigated using univariate and multivariate regression analysis. Results: Three-year overall survival, biochemical progression-free survival, and clinical progress-free survival were 88.89%, 62.96% and 77.78%, respectively. Preoperative symptoms of hematuria, urinary frequency, and dysuria were well alleviated after cystoprostatectomy. Moreover, FACT-P questionnaire scores at 6 months and 1 year after cystoprostatectomy were significantly higher than preoperative scores. Univariate and multivariable analysis (p < .05) showed that postoperative complication was the independent risk factor for the loss of postoperative QoL. Conclusions: Patients' QoL can be improved after cystoprostatectomy as the treatment for LAPC with the bladder invasion, which is associated with ameliorative urinary symptoms after the surgery. Besides, surgical complication is identified to be a risk factor for postoperative poor QoL.