In this paper, the laser diode (LD) fiber coupling method based on the wavelength multiplexing technique is used. Two different wavelengths of beams from two high power laser diodes are coupled into a single multi-mode fiber via collimating, wavelength combining, focusing and coupling to achieve high efficiently high power output. The output light beam from LD is collimated by using a section of the optical fiber with a diameter of 200μm. According to the basic principle of wavelength multiplexing, the wavelength coupling device is designed. The focusing lens set is designed with the related technical data of fiber and LD. And, two diode laser beams at 808nm and 980nm, light-emitting area of 100μm×1μm, output power of 2W（CW）LDs are coupled into a multi-mode fiber by the above method, with a core diameter of 100μm and a numberical aperture (NA) of 0.22. In the current work, for 808 nm LD and 980 nm LD at a operation current of 2.5 A, the total continuous power output is 4.05 W while the continuous power output is 3.25 W for the optical fiber laser, which gives a total coupling efficiency of as high as 80%.