In order to improve the measurement accuracy and repeatability of monocular vision camera, a closed-loop control method for the scanning mirror in laser scanning projection is proposed to improve the stability of the projected fringe position. The closed-loop control is carried out by using the feedback signal provided by the piezoresistive sensor integrated on the scanning mirror. At the same time, according to the temperature characteristic of piezoresistive sensor, a test system is designed to calibrate the relationship between piezoresistive output and temperature. By recording the piezoresistive feedback output value at different temperature, a table of the relationship between the feedback output and temperature is generated. In the temperature range from room temperature to 70 ℃, the scanning angle change of the scanning mirror decreases from 3.52° to 0.05°. By compensating the scanning angle of the scanning mirror, the 3D testing accuracy and the repeatability of the testing data of the monocular vision camera are greatly improved.