Aiming at the problems of high cost, low efficiency and low precision in traditional bearing measurement,a bearing measurement scheme based on machine visual calibration tool was proposed.In the solution, firstly camera was used to make a real-time photo of the bearing, then the caliper tool method was used to circularly fit the inner and outer diameters of the image. After the camera was calibrated, the inside and outside diameters of the bearing were measured, and the measurement result was displayed realtime with the program written by C#, implementing high-speed, stable, high precision,low cost size measurement.The experimental results show that the measurement method reaches the sub-pixel level, the measurement accuracy is higher than 0.008 mm, the standard deviation is less than 0.015, which meets the national standard, and the measurement speed is fast, the stability is high.