Abstract: Due to the fact that the accuracy of urinometer directly or indirectly affects the results of urine specific gravity monitoring in patients with chronic kidney disease and sports trainers, and the current calibration specification is missing, its calibration specification is specially formulated. Based on the built calibration device of urinometer, the mathematical model algorithm of the specific gravity of NaCl solutions is summarized, the calibration method of urinometer is proposed, the technical indicators are clarified, and the calibration cases are used to verify and analyze the relevant influencing factors. According to the calibration method, the verification results of temperature indication error, specific gravity indication error and specific gravity repeatability of urinometer are analyzed, and the characteristic evaluation conclusions are drawn. The calibration method of urinometer has been successfully constructed, which provides a useful reference for the preparation of “Calibration Specifications for Urinometer” and promotes the traceability and standardization process of urinometer.