To improve the quality of the reconstructed image of the holographic stereogram obtaines by the effective viewing angle image slice mosaic (EPISM) method, the stitching error is analyzed during synthetic parallax image generation by the traditional EPISM method, and the EPISM method with multiple reference planes is proposed. Theoretical analysis shows that there are no mosaicking errors in the synthetic parallax image of the part that coincides with the algorithm reference plane or optical axis on the three-dimensional object. The farther away the image reconstruction happen from the algorithm reference plane or optical axis, the more significant the synthetic parallax image error became. Reduction of the sampling camera interval can reduce errors to a certain extent. To further improve the EPISM method, the single algorithm reference surface of the traditional EPISM method is expanded into multiple, and the generated multiple combinations are recombined into parallax images to eventually obtain a synthetic parallax image with less significant errors. Simulation and optical experiment results show that the EPISM method with multi-reference planes can effectively improve the imaging quality of holographic stereogram.