【Objective】To compare the imaging features and early diagnostic value of high frequency color Doppler ultrasonography and X- ray mammography in patients with breast carcinoma in situ. 【Methods】 The clinical data of 55 patients with breast carcinoma in situ confirmed by operation and pathology were collected and analyzed retrospectively ， including high frequency color Doppler ultrasonography and X-ray mammography.【Results】Among 55 cases，28 cases were diagnosed as breast carcinoma in situ by high frequency color Doppler ultrasonography ，with the diagnostic accuracy rate of 50.9%；39 cases were diagnosed as breast carcinoma in situ by X-ray mammography，with the diagnostic accuracy rate of 70.9% . Statistical results showed that the diagnostic accuracy of mammography for breast carcinoma in situ was significantly higher than that of high frequency color Doppler ultrasonography（P=0.049）. The diagnostic accuracy of X- ray mammography was 67.3% and that of high frequency color Doppler ultrasonography was 47.3%（P=0.034）. 43 cases of breast carcinoma in situ were diagnosed by color Doppler ultrasonography and X-ray mammography ，and the diagnostic accuracy was 78.2% ，which increased significantly. 【Conclusions】 X- ray mammography is superior to high- frequency color Doppler ultrasonography in the early diagnosis of breast carcinoma in situ. The combination of the two imaging methods can play a complementary role in improving the accuracy of diagnosis of breast carcinoma in situ and reducing the rate of missed diagnosis.