Calcification of renal cysts is not a good sign. Renal cysts are usually evaluated by Bosniak grading to assess whether they are simple cysts, complex renal cysts, or have the possibility of cystic kidney cancer. The main assessment is whether the cyst fluid is clear, whether there is separation, whether the cyst wall is thin, whether there is calcification in the cyst wall, and whether there is tissue shadow. For simple renal cysts, the cyst wall is very thin, the cyst fluid is clear, there is no separation, and there is no tissue shadow. If there is calcification in the cyst wall of renal cyst, it is basically graded as Bosniak grade III, which should be given full attention, and CT plain scan plus enhancement should be done to effectively confirm whether there is a possibility of malignant lesion.