The invention discloses a wavelength correction type multi-beam-angle stepped reflector laser interferometer comprising a laser source, a spectroscope, a fixed stepped plane angle reflector, a measurement angle reflector unit, and a photoelectric detector group. The measurement angle reflector unit includes a measurement angle reflector and a precise displacement device. The laser source includes n parallel laser beams, wherein the n is larger than or equal to 2. The photoelectric detector group consists of n photoelectric detectors. The reflection planes of the fixed stepped plane angle reflector are n stepped planes; the space between each two reflection planes is expressed by a formula, wherein a k in the formula is a natural number. One beam of laser processed by the spectroscope is transmitted into one reflection plane and then is reflected to one photoelectric detector; and another beam of laser transmitted in the spectroscope is reflected by the measurement angle reflector and the spectroscope and enters the photoelectric detector. The laser interference phenomenon generated by the laser interferometer not only is associated with the laser wavelength but also is associated with the height difference value of the stepped reflection planes. The photoelectric detector group can detect displacement with the precision of a lambda/2n level. During the measurement process, the environment equivalent wavelength can be obtained by using the wavelength correction method, so that the measurement precision is improved obviously.