A new method was proposed to synthesize computer-generated hologram of three-dimensional object. According to the principles of paraboloid of revolution in three-dimensional Fourier space, spectra information of three-dimensional object was gathered. A series of projection images of three-dimensional object was recorded by circular scanning method, then the information of the projection spectra in several semi-circles form was extracted and encoded into computer-generated hologram based on conjugate-symmetric extension. In the traditional method, the spectrum information is extracted in a circular form from each projection. In the case of an equal number of projections, the proposed method can extract more spectrum information. So it can effectively improve utilization of each projection, and the quality of reconstructed image from computer-generated hologram. Experimental results validate the proposed method and its good performance.