Objective To investigate diagnostic value of multi-slice spiral CT in renal carcinoma. Methods Sixty four patients confirmed to suffer from kidney cancer by surgery pathology research object, retrospective analysis and summary were made according to the clinical data were, and diagnostic value of multi-slice spiral CT in renal carcinoma were analyzed. Results CT plain scan demonstrated there were 6 patients with high density, 19 patients with mixed density, and 23 patients with isodensity or slightly low density. CT enhanced scan showed that there 39 patients with significantly reinforced tumor, 17 patients with moderate irregularly reinforced tumor and 8 patients with mildly reinforced tumor, and enhanced scan of three phases showed fast forward reinforced characteristics of fast forward and quick backward. Spiral CT staging involved 40 patients at Stage I, 6 patients at Stage II, 8 patients at Stage III, 9 and patients at Stage IV, and the difference was no statistically significant when compared to that of pathological staging (P＞0.05). Conclusion Multi-slice spiral CT delivers high diagnostic value in renal carcinoma, its images show certain characteristics, it can improve the accuracy of diagnosis and staging ability of renal carcinoma, and it provides important information for clinical development of therapeutic schedule and prognosis evaluation, being worthy of popularization.