Objective To evaluate the predictive value of combination of computed tomography (CT) and immunohistochemical staining of bladder cancer tissue with HMGN5 protein to the risk of pelvic lymphonodus metastases. Methods 47 cases of bladder cancer who underwent radical cystectomy and pelvic lymph node dissection (PLND) between Jan 2015 to Dec 2017 were investigated, and the data of their CT of urinary system and pelvic cavity, pathology of pelvic lymph nodes and results of immunohistochemical staining of bladder cancer tissue with HMGN5 protein were collected and analyzed. Results The results of CT scanning of pelvic lymph nodes of 8 cases were positive, and 6 of them with pelvic lymphonodus metastases determined in pathology. The results of CT scanning of pelvic lymph nodes of 39 cases were negative, and 7 of them with pelvic lymphonodus metastases determined in pathology. The results of immunohistochemical staining of 15 cases were positive, and 12 of them with pelvic lymphonodus metastases determined in pathology. The results of immunohistochemical staining of 32 cases were negative, and 1 of them with pelvic lymphonodus metastases determined in pathology. Both of results of CT and immunohistochemical staining of 6 cases were postive, and 5 of them with pelvic lymphonodus metastases determined in pathology. Both of results of CT and immunohistochemical staining of 30 cases were negative, and none of them with pelvic lymphonodus metastasis determined in pathology. Conclusion Combination of computed tomography (CT) and immunohistochemical staining of bladder cancer tissue with HMGN5 protein may predict the risk of pelvic lymphonodus metastases. The two examinations should be suggested before radical surgeries, because the decisions of ranges of PLND may depend on the results.