Laser shock forming of metal sheet usually effects on the surface of work-piece in normal direction by laser beam, and produces shock wave force which is vertical to the surface of work-piece. But it is difficult to shock in normal direction during processing on the surface of forming camber, so it needs to study on oblique angle laser shock processing. LD31 forging aluminum alloy sheet is shocked by Nd-glass laser in the paper, model and mode of oblique angle laser shock processing is found, and transmitting characteristics of plasma stress wave is discussed. The experiment results show that the angle between input beam and sample normal is bigger, component of forces that parallel with sample surface is bigger, the deformation eccentricity is bigger and bigger. When the angle is bigger, the area of laser beam spot becomes bigger too, energy density becomes smaller, deformation becomes shallower.