Fixture is an instrument used for parts clamping. When detecting parts on CMM and image measuring instrument, fixture plays a vital role. In order to ensure the accuracy of the measured surface relative to other positions, it is necessary to first determine the position of the parts on the machine table, and then the size of some workpieces needs to be measured by the probe. When the probe touches the parts, the parts may shake without clamping, and the measured value is not the value initially positioned, thus affecting the measurement accuracy.