Let A∈Cm×nr and ∈Cm×nr,then A+∈Cn×mr and +∈n×mr.The generalized polar decompositions of A+ and + are A+=QH and += respectively.The H and are n×m subunitary matrix.With the singular value decomposition,the perturbation bounds for semi-positive definite polar factor of Moore-Penrose generalized inverse matrix A+ under unitarily invariant norm ‖·‖ are obtained.