The new bone fixator is an external fixator that can be used to treat fractures, correct skeletal deformities and other conditions, and requires prescription software to calibrate and prescribe treatment. In this paper, a systematic calibration method is designed for a new external fixator based on binocular stereo vision. The method first calibrates the binocular image of the external fixator, finds the internal and external parameters of the camera and corrects the image, then uses the principle of binocular stereo vision to solve for the coordinates of the key points in the processed image and uses the key point coordinates to calculate the length of the fixator linkage. The method was validated to be able to control the error within 05.mm. The data calculated by this method can be used directly by the prescription software when designing the treatment plan, which is important for optimising the process of using the new external bone fixation frame.