Abstract: Aiming at the long time and unstable problems of vertex synchronization in the existing 3D information hiding algorithms, a synchronous 3D point cloud information hiding based on projection sampling is proposed. The main contribution is presenting a scheme for point cloud projection sampling, which eliminates the influence of watermark embedding on vertex ordering, and achieves complete synchronization of vertex order. So this method completely resists reordering attacks. The point cloud projection sampling method projects all vertices vertically onto the XOY plane to get the sampling points whose total number is controlled by the resolution of the projection surface. The vertex synchronization is achieved by accessing all the sampling points by rule. In addition, this paper embeds the secret data into the Z-axis coordinates and the color component values of the vertex at the same time. Due to unchanged X and Y-axis coordinates this method ensures the stability of vertex synchronization for large embedding capacity. It is a blind extraction method because the original model is not needed during the extraction. The experimental results show that this method has large capacity and good imperceptibility. It can completely resist reordering attack, X and Y-axis translation, also it has the ability to resist scaling attacks in X and Y-axis, additive noise and shear attacks.