Abstract: Objective: To estimate the value of CT mapping in diagnosis of renal angiomyolipoma(RAL).Methods: Twenty-two cases of RAL were collected,10 of which were proved by pathological examination and 12 cases by at least 6-month following up.All the cases were performed routine CT Scan.Fourteen cases received enhanced CT scan,5 cases target scan and 3 cases pixel CT value measuring.Results: The pathologic characteristics of CT were spotty and streak soft tissues in the fatty density and the adipose tissues were always eccentric and of the shape of irregular honey-comb.The growth manifestations of RAL in CT were multiple centers,bilateral and protruding outward growth or creeping under the capsule.Conclusions: The detection of fatty density was the key to diagnosis of RAL.Multiple lesions,bilateral or protruding change and the defect like teeth of a cogwheel along the edge of parachyma were of great value to the diagnosis.