The development process of beam scanning technology is reviewed. The characteristics of beam scanning technology of micro-electromechanical system (MEMS) and mechanics-free electrical control modes are analyzed. And the technology advantages of those two technologies are compared synthetically. In high-speed optical communication system, the influence of chromatic dispersion characteristics of the technology on bit error rate of high-speed optical communication system must be considered due to the widely application of beam scanning technology of mechanics-free electrical control mode.