Abstract: The laser wire (LW) method has been demonstrated as an effective non-interceptive technique for measuring transverse electron beam size of CW FELs and ERLs. To measure the beam size of a CW DC gun, which is built as an electron source of FEL-THz facility in China Academy of Engineering Physics (CAEP), a high repetition LW system is proposed. The first prototype system is going to be installed at the exit of the DC gun, where the energy of electron beam is extremely low. In this paper, the LW system adapted to the FEL beam parameters is discussed, and the main parameters are given. With numerical calculation and Particle-in-Cell simulation, the high repetition LW system is proved to be lower-cost, higher-precision, faster-scanning and lower-influence than normal LW. The experiment proposal of the first high repetition LW is also introduced.