A method for choosing angle of reference beam in computer-generated holograms based on spatial frequency analysis of principle fringe pattern was proposed. The rules for reconstructed image rightly were obtained through analyzing the spatial frequency of principle fringe pattern. The angles of reference beam in the holography reconstructed system based on spatial light modulator were computed. The holograms of one image plane with size of 22.5 mm×26.1 mm were generated at the distance of 1 000 mm when different angles of reference beam were chosen. The digital and optical reconstructed experiments were conducted respectively. The results indicate that the angle of reference beam must be chosen in the range which is from 0.893 8° to 1.398 0° in order to achieve good quality of reconstructed images. If the angle of reference beam is smaller than 0.893 8°, the reconstructed image and the conjugate image could not be separated completely, whereas the reconstructed image would overlap with the conjugate image of the next order if the angle of reference beam is larger than 1.398 0°. The experimental results validate the theoretical analysis very well.