Objective: To evaluate the value of ultrasonic examination and molybdenum target X-ray mammography for early diagnosis of breast cancer, so as to improve the efficiency of early breast cancer detection. Methods: The clinical data of 528 female patients with early-diagnosed breast cancer were collected. Of the patients, the lesions in 132 cases, which were both mammographically and clinically occult, were diagnosed by B-ultrasonic examination, and in 396 cases were identified by molybdenum target X-ray mammography. The clinical and imaging characteristics, surgical procedure and histopathological profiles, as well as molecular biological markers and types between the patients diagnosed by the two examination methods were compared. Results: Comparison between the two groups of patients demonstrated that ultrasonic examination was more likely to detect the lesions than molybdenum target X-ray mammography in young, premenopausal, and Han nationality (vs. Uyghur nationality) women, in dense breast tissues, and of BI-RADS category 4 in breast imaging (all P<0.05); compared with molybdenum target X-ray mammography, patients preliminarily diagnosed by ultrasonic examination were more likely to undergo breast-conserving surgery and had a low positive rate of lymph node metastasis, and ultrasonic examination was more likely to find the lesions that were less than 1 cm, solitary and well differentiated, and more likely to find the early-stage invasive breast cancer (all P<0.05); ultrasonic examination had high detection rate for ER-positive or luminal A breast cancer, while molybdenum target X-ray mammography had high detection rate for Her-2-positive or Her-2 subtype breast cancer (all P<0.05). Conclusion: Ultrasonic examination has higher detection rate than molybdenum target X-ray mammography for the early-stage breast cancer with low degree of invasiveness and malignancy in dense breast tissue, but both have their advantages in detection of early breast cancer of molecular subtypes. So, combined application of the two methods can increase the early detection rate of breast cancer.