The laser beam is considered as an important technique tool for 3D measurement. For precise 3D measurement, the spatial pose of a laser beam must be calibrated before measurement. To make the spatial pose of a laser beam more precise, an optimization method of a laser beam is proposed in this paper. Utilizing the points measured by a laser tracker as benchmark, the more precise parameters of the laser beams can be obtained through Levenberg-Marquarelt algorithm. Comparing improved results with initial ones, the effect of the method can be shown obviously. The method is considered to be a feasible way to optimize the laser beam through experiment verification.