In order to protect copyright of 3D model, this paper present a kind of algorithm of holographic digital blind watermark for 3D point cloud model based on discrete cosine transform. Firstly, affine invariant preprocessing was used for the 3D model. Then, coordinates of the 3D model were switched to spherical coordinates with the angle value in an ascending sort order. The distance from the object center to the vertices was taken as the watermark embedding object to embed the watermark in the 64 × 64 array. Holographic watermarking technology turned binary watermark image into holographic watermark. By discrete cosine transform, the intermediate frequency part of holographic watermark was embedded with the watermark through inverse discrete cosine transform to realize the transformation from the frequency domain to the spatial domain. The proposed algorithm belonged to blind watermark and had the high performance of the watermark robustness. Also, the performance of invisibility and stability was enhanced because the watermark was embedded in the intermediate frequency part. The algorithm can obtain the watermark from the 3D model successfully, and also the holographic watermarking technology can protect copyright of 3D model better.