Abstract: Objective To evaluate the diagnostic value in small breast tumour with CT.Methods 34 cases of small breast tumour were confirmed by operation or pathology underwent plain CT,21 cases underwent enhance CT scanning. Results 21 cases were maligant tumour and 13 cases were benign tumour, the diagnosis accuracy rate of CT was 88.2 %. Maligant tumour had nonsmooth edge and thom sign, in most cases CT density value increased most within one minute. Benign tumour had smooth edge, the mass density is uniform. Conclusion Plain CT and enhanced CT contributed to discovery and diagnosis of small breast tumour.