Objective:To analyze the inter-observer consistency of Smart 3D super microvascular imaging (Smart-3D SMI) in evaluating the blood flow of breast lesions.Methods:Prospective study on Smart-3D SMI images of 225 cases of continuous breast lesions in Peking Union Medical College Hospital from January to December 2018. Two sonographers conducted qualitative evaluation of vascular architecture(VA) under Smart-3D SMI, and took the mean value of three measurements evaluations of vascular index(VI). Weighted Kappa was used to test the consistency of the vascular architecture, and Bland-Altman scatter plot was used to calculate the 95% consistency limit of the measured data for the VI value. Spearman correlation coefficient was used to analyze whether the absolute difference of VI between observers was correlated with the mean value of VI.Results:The Weighted Kappa coefficient of Smart-3D SMI for the evaluation of VA by two sonographers was 0.839 (95% CI was 0.795-0.881, P<0.001), showing strong inter-observer consistency. Bland-Altman plot analysis of VI value showed that the value of 95.11% was within the clinically acceptable range and had good consistency, and there was a correlation between the difference of VI value between observers and the value of VI mean ( r s=0.639, P<0.001). Conclusions:There is a good inter-observer consistency in evaluating the blood vascular architecture and quantitatively measuring the blood flow abundance by Smart-3D SMI.