Abstract: According to the principle of X-ray coded aperture imaging, the ground simulation imaging system was set up. On the basis of it, the theoretical calculation method of the yield and the orientation of near-earth space nuclear explosion was established. The relationships between the system response (gray value) and the intensity of X-ray, the center of mass coordinates of the reconstruction imaging and the X-ray incidence angle were presented, and the nuclear explosion yield and orientation simulation detection experiments were carried out. The experimental results are consistent with the theoretical calculation results, so the feasibility of using X-ray coded aperture imaging technology in near-earth space nuclear explosion detection is verified. Compared with multi-pinhole imaging system, X-ray coded aperture imaging system has higher detection sensitivity, signal-to-noise ratio and anti-jamming ability.