The computer-generated hologram called digital hologram as well,which is fully digitized,is laid store by people as a kind of new 3D display technology. But compared with optical hologram,hidden surface of scene is a special problem of digital hologram. This problem doesn't be solved well before. To solve it,first the decay of reconstructed image quality caused by hidden surfaces is analysed based on the theory of digital hologram. The conclusion is drawed which is the hidden surfaces must be removed when computing holograms of complex scenes. Secondly a method to remove hidden surfaces is presented,which is to find the collection of nearest intersection points on virtual rays connecting every sample point of scene to that of hologram. Finaly the results of simulation are presented. High quality digital hologram will be made when the method presented employed.