A calibration method of the included angle measuring system based on the autocollimation contrast system is proposed. This method is used to improve the accuracy of the included angle measuring system. Therefore, it can accurately measure the deformation of the spacecraft structure in the space environment. The calibration coefficient is achieved by calibrating the included angle measuring system, and the coefficient is evaluated by simulation data. Results shows that the measuring range of the included angle measuring system can be up to ± 25′ and the measuring resolution can be up to 0. 1″. Experimental results show that the calibration method is simple and convenient with high accuracy. It proves that the measurement accuracy of the angle measuring instrument reaches ± 0. 2″ by computing the absolute value of the difference between the measured results and certified value. In general, the accuracy of the angle measuring instrument after calibration meets the requirements of satellite utilization. This method can provide technical support for the study of micro deformation of satellite structures in orbit.