Abstract: Objective: According to the CT scan image and the performance of three-dimensional reconstruction,to study the diagnostic value and type of MSCT reconstruction in small renal carcinomas.Materials and Methods: A retrospective analysis was done for 43 cases of small renal carcinomas which received MSCT examination and confirmed by pathology in our hospital,analysis and type them with their performance in the CT examination.Results: There are 16 cases of small renal carcinoma of protruding type,their performance of CT examination are the tumors convex to the outline of the kidney or convex to the renal pelvis or calyx,when in enhancement CT scan,the contrast agent in the tumor are fast flowing in and fast flowing out which are the performance of malignant tumor;There are 6 cases of small renal carcinoma of inside renal parenchyma type,their performance of CT examination are the tumors limited in the renal parenchyma,when in enhancement CT scan,the performance of the tumor are f the typical performance of malignant tumor;There are 9 cases of small renal carcinoma of cystic type,their performance of CT examination are that when in enhancement CT scan,there are multiple enhanced uneven thickness stripes or small pitchy enhancement in the tumor;There are 5 cases of small renal carcinoma of multiple type,their performance of CT examination are that there are multiple small renal carcinomas in one kidney.Conclusion: Multi-slice spiral CT scan with 3D reconstruction image post-processing techniques can accurately and effectively diagnose various types of small renal carcinoma.