Objective To compare the diagnostic value of automatic breast ultrasound system and conventional ultrasound in the breast cancer. Methods The preoperative data of conventional ultrasound and ABUS were retrospectively analyzed in 126 patients with 132 breast nodules. The imaging features of conventional ultrasound and ABUS coronal section were analyzed . According to the pathological results as the gold standard, The diagnostic efficacy of ABUS alone and conventional ultrasound and their combination in the diagnosis of breast nodules were calculated and compared. Results Among the 132 breast nodules that were diagnosed by pathology，60 nodules were malignant and 72 nodules were benign. The sensitivity，specificity，predictive and negative predictive rate of uneven edge detected by US in the diagnosis of breast malignant were 86.7%，62.5%，65.8%，84.9%. The sensitivity，specificity，predictive and negative predictive rate of convergent sign detected by ABUS in the diagnosis of breast malignant were 60.0%，94.4%，90.0%，73.9%. The sensitivity，specificity，predictive and negative predictive rate of combination of the two examination were88.3%，59.7%，65.5%，89.6%. The result indicate that the sensitivity of conventional US was higher than ABUS in the diagnosis of malignant breast nodules，the specificity of ABUS was higher than conventional US and the combination of two examination，the difference was statistically significant（P＜0.05）. Conclusion ABUS could provide more comprehensive image information than conventional US， and has high specificity for breast cancer diagnosis，it could be used as a supplement to conventional US in the diagnosis of the breast cancer.