A high efficient terminal polarization-converting system is designed based on combination of axicons and wave plates to transform naturally polarized laser to linearly polarized laser at real time to resolve difficulty of generating high power linearly polarized laser. Energy conversion efficiency is 97.3% with an enhancement of extinction ratio from 18.3% to 99%. The system also keeps excellent far field divergence. The experiment proves that this polarization-converting method will not affect laser structure. The controlling method is, feedback and controlling system is not needed. The property is stable and reliable. It can absolutely be applied to the polarization-conversion of high power laser.