PhysGaussian is an innovative unified simulation rendering pipeline capable of seamlessly generating both physics-based dynamics and realistic rendering. It leverages a custom material point method (MPM) to combine 3D Gaussian kernels with physically meaningful motion deformations and mechanical stress properties, evolving through continuous mechanics principles. The product boasts seamless integration between physics simulation and visual rendering, with both components utilizing the same 3D Gaussian kernel as their discrete representation. This eliminates the need for triangular / tetrahedral meshes, Marching Cubes, or any other geometric embedding, underscoring the "what you see is what you simulate" principle.