The invention provides a method for rapidly and accurately adjusting interference of two beams. The method includes the following steps of adding a sixth light guide lens to one arm of an optical beam splitter where interference of the two beams is produced, placing a non-degenerate optical cavity between the sixth light guide lens and a first detector, transforming a transverse mode size of a laser beam a with a lens group a so as to achieve mode matching between the laser beam a and an eigenmode of the non-degenerate optical cavity, transforming a transverse mode size of a laser beam b with a lens group b so as to achieve mode matching between the laser beam b and the eigenmode of the non-degenerate optical cavity, scanning a relative phase of the two laser beams, and observing and checking interference efficiency with a second or third detector. The method is convenient to operate, high in practicality, and high in adjusting and interfering accuracy, and a device used for the method is simple.