The invention relates to an anti-return main oscillation power amplification pulse laser, which sequentially comprises a seed semiconductor laser, a return light processor, a first-stage amplifier, a first-stage return light processor, a second-stage amplifier, a second-stage return light processor,..., an n-stage amplifier and an n-stage return light processor. The return light processors are designed to ensure forward transmission of signal light, prevent reverse transmission of the signal light, prevent reverse transmission of non-linear laser, ASE light and return light outside a light path, and monitor the return light. The laser does not limit the starting time of the Seed LD, can realize continuous adjustment of the pulse width and the frequency, does not need a complex structure and calculation, is low in cost and compact in structure, can process return light of each wave band, effectively protects the laser, and prolongs the service life of the laser.