This paper proposed a novel robust oblivious watermarking scheme in the spatial domain suitable for 3D mesh object，which combines the principal component analysis (PCA) method with construction of cone bins.Firstly，PCA is used to calculate the eigenvectors of covariance matrix of vertex coordinates.Then the object is rotated and translated so that its center of mass and the three eigenvectors that coincide with the origin and the three axes of the Cartesian coordinate system.Subsequently，many cone bins are constructed，each bin center according to two angle parameters of spherical coordinate produced by pseudorandom number generators and the vertices are classified into the appropriate cone bins.Each cone bin is divided into a number of sub-bins in order to embed the watermark bit，and the size of sub-bin can make tradeoff between invisible and robustness.Experiment results show the remarkable ability of the proposed mechanism to resist against various attacks such as adding noise，clipping，similarity transform and vertex re-ordering.