In order to realize the quasi-real-time calculation of holograms, a fast algorithm of computer generated holograms based on a multi-graphic processing unit (GPU) in Matlab is proposed. This method makes full use of the simplicity of Matlab programming and the high computational performance of GPU, and thus the computing time of holograms is effectively saved. The simulation results show that the computing speed of the proposed method is about two orders of magnitude higher than those of the traditional calculation methods.