Abstract: Cystic renal masses account for only 15% of all renal masses, and most malignant cystic renal masses are less invasive, with a mortality rate far lesser than that of malignant solid renal masses. Inconsistency in imaging diagnosis leads to the removal of many benign and inert masses, thereby causing unnecessary surgical injury. The Bosniak classification system is based on computed tomography findings to categorize the degree of malignancy of cystic renal masses and guide clinical practice, and this system is widely used. With the innovation of ultrasound technology, the application of the Bosniak classification system in the diagnosis of cystic renal masses has good clinical value. This study reviews the diagnosis and clinical treatment principles based on the Bosniak classification system for cystic renal masses using ultrasound, contrast-enhanced ultrasound, and superb microvascular imaging (SMI).