The verification of external diameter micrometer is still in the stage of laboratory verification.The detection efficiency is low and the measurement result is easily affected by human factors. In order to solve these problems, indication verification device for external diameter micrometer based on machine vision is designed. The free degrees of external diameter micrometer were restricted by the fixed structure to ensure the stability of micrometer in the process of verification. The micrometer line template was established and the micrometer positioning was accomplished accurately by using the image method. The automatic clamping of the external diameter micrometers microdrum was realized by the rotary fixture and the movement of the micrometer was driven by it. The collection of the External Diameter Micrometer indication surface and the reading of the scale was completed by the vision system.The device is applied to reduce the manual error and to improve the verification efficiency of micrometer and the credibility of the verification results.