To explore the clinical characteristics and outcome of hydronephrosis associated with advanced or metastatic colorectal carcinoma. Clinical data of 311 patients with locally advanced or metastatic colorectal carcinoma between June 2017 and March 2020 in National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital & Shenzhen Hospital were retrospectively collected. Thirty-nine patients with hydronephrosis diagnosed by CT scan were analyzed. Kaplan-Meier method was used for survival analysis, Log rank method was used for comparison of survival between the two groups with or without hydronephrosis, and univariate and multivariate analyses was performed by Cox proportional risk regression model. The incidence rate of malignant hydronephrosis associated with metastatic colorectal carcinoma was 12.5% (39/311), 26 were male, and 13 were female. The median age was 43 years (23-74 years). Among the 39 patients, 29 had unilateral hydronephrosis and 10 had bilateral hydronephrosis. Eleven patients with hydronephrosis at the initiate diagnosis, 28 patients with hydronephrosis at relapse or advanced course, and the median time to hydronephrosis was 17 months (4-62 months). The disease control rate (DCR, 77.8% and 84.6%, respectively) and progression free survival (PFS were 6 and 7 months) were not significantly different between patients with hydronephrosis and without hydronephrosis received the first-line chemotherapy (>0.05). The median overall survival (OS) after presence of hydronephrosis was 26 months (95% 8.3, 43.7). Multivariate analyses showed that the blood vessel invasion (LVSI) was an independent risk factor for OS (<0.05). Malignant hydronephrosis had no effect on the efficacy of the first-line chemotherapy and PFS of patients with colorectal carcinoma received the first-line chemotherapy. LVSI was the independent prognostic factor for OS of patients with malignant hydronephrosis.