in this paper, a simple, economical and pratical collimation method -single lens collimation method of semiconductor lasers is calculated theoretically and experimented on from Gaussian beam. The calculation is in accordance with the results of enperlment.Thus it show that when using a lens whose relative aperture (D/f)is bigger and choosing a suitable realative position between the lens and the semiconductor laser we can get the quite satisfactive collrmation effect.