Rotator cuff tear is a kind of frequently-occurring disesae,and ultrasonography is the prefferred examination method for the disease,but the organization of hematoma in the nidus leads to false-negative in most cases.A new nonlinear approach based on statistical analysis of ultrasound radio-frequency(RF) signals is developed for identifying the lesion to improve the diagnostic accuracy. Firstly, the raw RF data is scanned and saved in the second harmonic mode,then the region of interest(ROI) and reference region (RR) are selected in one frame by applying the band-pass filter. The root-mean-square value of second harmonic in one or more cycles within ROI and RR are calculated and compared by Kolmogorov-Smirnow test for the p-value.The relative p-value is estimated by comparing the ROI and RR. The proposed method solves the problems of high subjectivity in identifying complex tissue and requisiting rich clinical experience in the ultrasound examination with accurate measurement and easy implement.