Abstract: In order to increase the coupling efficiency of diode laser arrays side-pumped slab laser and efficiently the mode of slab laser, the wave-guide coupling system with the high coupling efficiency has been designed by means of a ray-tracing method. The large end surface of the coupling system is connected with high power diode laser arrays, and the small end surface is connected with the laser slab. The experimental results show that the optical coupling efficiency was 85%, and an output beam with a uniform profile has been achieved in the slab. The wave-guide systems have been used in laser experiment, and the near diffraction-limited beam has been obtained in the slab laser.