Objective To explore the value of differentiating benign and malignant breast tumor by the ultrasonic elastography（UE）and Two dimensinonal ultrasound. Methods 104 patients with 119 tumor were examined by the UE and Two dimensinonal ultrasound,Their disgnostic results is compared with the post-operative pathological results. Results 68 patients with 80 tumor were in the benign group and 36 patients with 39 tumor were in the madignant group.The sensitivity,specificity and accuracy for the UE diagnosing breast cancer is 87.1%,96.0% and 92.6% respectively,and the Two dimensinonal ultrasound diagnosing breast tumor is 82.1%,88.8% and 85.7%. Conclusions It is important value that the benign and malignant breast tumor were differentiated by the UE.