The methods on computer-generated hologram coding and digital reconstruction for descrete object wave are discussed and the frequency spectrum positions of zero-order image, original image and conjugate image are analized. The proposed coding and decoding scheme can separate the spectrum of each image and record multi-object wave data in the same computer-generated hologram. The simulation results show that the method by preprocessing the original object wave data and controling parameters to seperate effectively the frequency spectrum is simple and easy and the quality of the reconstructed image is good. As one of the coding parameters, carrier coefficient can effectively control the shift position of each spectrum component. Improper parameter setting can lead to be not able to extract effctive spectrum. So it can also be used as an encryption parameter.