Optical forces on moving atom were investigated in micro-cavity using fully quantum theory. In terms of the models of moving atom interacting with micro-cavity field, using algebraic dynamics method, the Hamiltonian can be diagonalized by introducing a canonical transformation. The expression of evolution operator of the system and reduced density operators are calculated straightforwardly. Analytical expressions for the forces are obtained, and the forces are discussed for a traveling-wave field and a standing-wave field respectively.