An centering alignment technique of collimation lens group based on the optical axis of primary mirror is introduced in this paper, so as to meet up with the deviation requirements in the assembly of high-quality Common Path Optical system. A non-aberration system is designed in the first place in order to analyse the conjunction between the Wave-front aberration and eccentric error,then construct the simulation model of cassegrain system and collimation lens group based on test result,formed the eccentric error mapping relationship between the two variables. The collimation lens group is then assembied and aligned on the basis of the axis of the aspheric primary mirror. The technique has been verified through both simulative tests and actual measurements, and the results suggest the eccentric error is less than 0.04mm, and the Common Path Optical system Wave-front aberration RMS less than 0.03um.