A summarized analysis of computer-generated hologram algorithm of three-dimensional (3D) virtual object is presented. Based on the analysis results, 3D object surface is deemed to be a combination of right triangular area units with different shapes and locations. A convenient generation algorithm of computer-generated hologram is derived, and a calculation example of computer-generated hologram of smooth surface of 3D object is also presented. Based on sampling theory, the algorithm of calculating computer-generated hologram of diffuse 3D object is studied, and an example of computer-generated hologram of diffuse 3D object is given.