In order to control the propagation of high power laser beam and make the laser beam focus at any position without quality degradation,the change of high-power laser focal positions was investigated.The proposed research was based on the theory of lens-focusing and laser self-focusing in nonlinear media.Influences of different kinds of factors on the focal position were analyzed.Through numerical solution of the nonlinear Schrdinger equation,the relationships of the focal position with input power,initial waist and focal length of lens were obtained,and thus the method to control the beam focal position was found.The numerical simulations coincide with the theoretical analysis.