Objective：To explore the predictive values of viscoelasticity（VE）for benign and malignant breast imaging reporting and data system（BI-RADS）4 breast nodules. Methods：A total of 102 patients（105 nodules）with BI-RADS 4 breast nodules diagnosed by conventional ultrasound in Wuxi People’s Hospital Affiliated to Nanjing Medical University from February 2024 to March 2025 were retrospectively analyzed. VE and shear -wave elastography（SWE）were used to measure ultrasound parameters. Through the system measurement tool“Shell”，the Shell thickness（n）was manually adjusted from 1.0 to 5.0 mm at an interval of 1.0 mm to obtain the peritumoral ultrasound parameters，and the differences of ultrasonic parameters between the two groups were compared. The receiver operating characteristic（ROC）curve was drawn to analyze the diagnostic efficacy of VE，SWE ultrasound parameters and conventional ultrasound BI-RADS classification alone or combined to predict the nature of BI-RADS 4 breast nodules. Results：A total of 105 BI-RADS 4 breast nodules were selected and divided into the benign group（n=58）and the malignant group（n=47）according to the pathological results. The diagnostic value of Shell2.0 maximum elastic modulus value（Emax）was the highest in the two groups of SWE ultrasound parameters. When the cutoff value was 89.48 kPa，its area under the ROC curve（AUC）for predicting the benign and malignant of BI-RADS 4 breast nodules was 0.709，the sensitivity was 53.20%，and the specificity was 84.50%. The diagnostic value of Shell3.0 maximum viscosity value（Vmax）was the highest in the two groups of VE ultrasound parameters. When the cutoff value was 5.77 Pa·s，its AUC for predicting the benign and malignant of BI -RADS 4 breast nodules was 0.750，the sensitivity was 70.21% ，and the specificity was 72.41% . When Shell2.0 Emax and Shell3.0 Vmax were combined with BI - RADS classification to predict the benign and malignant of BI -RADS 4 breast nodules，the AUC value increased to 0.941，with a sensitivity of 93.60% and a specificity of 93.10%，and the difference was statistically significant（P ＜ 0.05）. Conclusion：VE peritumoral parameters alone have high diagnostic value in predicting the benign and malignant of BI-RADS 4 breast nodules. VE，SWE technology combined with conventional ultrasound BI-RADS classification has the best diagnostic efficiency for the benign and malignant of BI-RADS 4 breast nodules.