Objective: Chemotherapy drugs such as platinum may cause damage to the renal function, creatinine clearance (Ccr), as a "golden standard" indicator in clinical evaluation of renal function, was limited in application due to complicated detection steps. By detecting the expression of serum Cystatin C (Cys C), Ccr and urinary micro-albumin (UMA), this study was designed to analyze and discuss their roles and status in renal function evaluation for cancer patients before and after chemotherapy with platinum. Methods: We retrospectively reviewed 110 patients who receiving platinum-containing protocols or non-platinum-containing ones, and got the expression of Cys C, Ccr (was calculated by Cockcroft-Gault equation) and UMA, then analyzed whether there were differences for Cys C,Ccr and UMA in those patients; for patients with mildly impaired renal function (Ccr between 50–75 mL/min), whether there were differences for Cys C and UMA before and after chemotherapy with platinum. Results: There was statistical significance for Ccr, Cys C and UMA in patients who receiving platinum-containing protocols (85.01 ± 28.40) vs (76.79 ± 26.63) mL/min, (1.49 ± 0.50) vs (1.80 ± 0.84) mg/L and (14.30 ± 9.15) vs (16.90 ± 10.95) mg/L, P = 0.00, 0.00 and 0.01), and no statistical significance for those receiving non-platinum-containing ones (89.45 ± 29.69) vs (86.78 ± 27.96) mL/min, (1.51 ± 0.78) vs (1.63 ± 0.73)mg/L and (17.31 ± 10.46) vs (16.59 ± 8.33) mg/L, P = 0.45, 0.07 and 0.57); and there were also significant differences for Cys C for patients with mildly impaired renal function before and after chemotherapy (1.68 ± 0.55) vs (2.04 ± 0.68) mg/L, P = 0.03), while no statistical significance for UMA for the same ones (21.11 ± 10.06) vs (21.22 ± 8.81) mg/L, P = 0.93). There were statistical significance both for Cys C and UMA before and after chemotherapy in platinum-containing group, but the AUC for Ccr and Cys C is greater than that for UMA (P < 0.02). Conclusion: Cys C and UMA can both access renal dysfunction early after chemotherapy, but Cys C is more sensitive than UMA in reflecting early renal dysfunction, so Cys C can replace Ccr and become a reliable indicator in the assessment of renal function for cancer patients before and after chemotherapy especially with platinum.