Aberration correction method of off-axial beam

The invention discloses an aberration correction of an off-axial beam. The method comprises the steps of establishing a planar rectangular coordinate system and deflecting a nonplanar reflection component in a single direction which corresponds with the planar rectangular coordinate system; respectively obtaining incident parameters in an x-direction and a y-direction according to deflection angle of the nonplanar reflection component along a single direction; calculating near-axis transmission matrixes in the x-direction and the y-direction according to the incident parameters; and obtaining the focal length of an added cylindrical lens according to the near-axis transmission matrixes and a transmission matrix of an emergent plane after the cylindrical lens is added. According to the aberration correction method of the off-axial beam, through adding the cylindrical lens, output beam quality and mode matching degree of a laser are improved.