Objective: To accurately describe the growth of human renal clear cell carcinoma.In our earlier research, the growth model of renal tumors is linear and is not accurate.A better growth model is needed.Methods: There patients under surveillance for more than ten years with renal tumors were analyzed.Tumor size and time were recorded in each observation.Curve fitting of renal tumor growth was performed in Growth model (L=e).Logarithmic transformation was used to linearize the curves.Through linear mixed model, regression analysis was completed with the initial tumor size and observation time as independent variables.