Objective: To investigate the efficacy and the influence factors of sunitinib as first-line treatment in patients with metastatic renal cell carcinoma (mRCC). Methods: Clinical data of mRCC patients with sunitinib administered as the first line treatment from August 2008 to December 2015 were retrospectively reviewed. The efficacy and the influence factors of sunitinib treatment was analyzed using the Kaplan-Meier method and Cox proportional hazards models. Results: In all 166 patients who received sunitinib as first-line treatment, objective response rate was 31.9%, disease control rate was 84.3%. The median progression free survival (PFS) and overall survival (OS) were 11.0 months (95% CI: 9.0-14.0) and 28.0 months (95% CI: 19.0-33.0), respectively. Multivariate analysis showed that pathological types (clear cell carcinoma vs non clear cell carcinoma, HR: 1.889 vs 2.353), time from diagnosis to treatment(<1 year vs ≥1 year, HR: 0.293 vs 0.322) and the number of metastatic sites (1 vs ≥1, HR: 2.360 vs 4.351) were the independent prognostic factors for PFS and OS (P<0.05). Conclusions: The efficacy of sunitinib as first-line treatment in patients with metastatic renal cell carcinoma is similar to reports at home and abroad. The patients with renal clear cell carcinoma, time from diagnosis to treatment> 1 year, and only one metastatic site would get better PFS and OS.