In this paper, a dual-stage curved surface scanning measuring device is developed. The purpose is to solve the contradiction between the high precision and the large range of the sensors, which makes it possible to measure the curved surface with a large height difference. A dual-stage measurement system is used to expand the range of the high-precision sensor so that a scanning measurement for curved surfaces with a large range and high-precision is realized. The dual-stage measurement system uses a voice coil motor to drive the flexure hinge to move the high-precision sensor in a straight line, so the measured surface can be kept within the measurement range of the high-precision sensor. The measurement data of the high-precision sensor is taken as the first-stage measurement data, and the measurement data of displacement of the flexure hinge by the high-precision grating encoder is taken as the second-stage measurement data. The information of the measurement point can be obtained by processing the data of the dual-stage measurement system, and the range of 5 mm can finally be realized. At the same time, the high-precision grating encoder is also used as the feedback device of the servo system. Then, the performance of the dual-stage measurement system is evaluated, and the measurement uncertainty is analyzed and calculated. Finally, experiments are carried out on the large range scanning capability of the measuring device, which proves that the device has the ability of large range scanning measurement.