A new method for side pumping of double-clad fiber lasers through reflection of micro-prism is described, which can pump the light sources from LDs, especially LD arrays, into double-clad fibers easily and effectively. Advantages of this technique include no destruction of inner-cladding, high pumping efficiency, simplicity, low cost, easy industrialization and so on. The mechanism and the application method are introduced and the theoretical coupling efficiency is given (up to 90%). Then primary experiment is made to verify the method and 50% coupling efficiency is gotten. The parameters of the prism and the applied areas is analged.