Intensity correlation interferometry, which exploits the high-order correlation characteristics of optical fields to obtain the spatial angles of astral bodies, is expected to achieve high-precision measurement of angular positions of pulsars. However, conventional intensity correlation measurement requires coherent detection, which imposes an extremely high requirement on the temporal resolution of detectors. In this paper, intensity correlation interferometry for astral observation angle based on spatial modulation is proposed. The optical field is spatially modulated by a modulation screen located in front of the detector, and the modulator screen is rotated to obtain second-order interference fringes. A second-order correlation function is derived theoretically for the case when there is an angle difference between the screen modulators of the two optical paths. On the basis of the theoretical results, a two-mirror experimental scheme is designed to verify the results obtained by visible light experiments. The experimental results are consistent with the theoretical analysis results. This method, greatly reducing the temporal resolution requirement on detectors, is significant for China’s fulfillment of spacecraft autonomous navigation in the future.