To get better EDFA performance, we have to improve the coupling efficiency of semiconductor laser diode(LD) and fiber optic; also, increase the LD¡¦s power to achieve. There are plenty of ways to have higher coupling efficiency out there. Some of them even can reach 90% or better coupling efficiency. However, because of light field property, high-power LD output will not be able to apply to high coupling efficiency structure. Therefore, using cascaded fiber can improve coupling efficiency and maintain its characteristic in high-power laser output environment. Cascaded fiber is connecting SMF and GIF together. Although cascaded fiber can increase high-power LD output of coupling efficiency, it has 5% to 10% of loss during manufacture because of the inspect error of melting surface. We use CCD to observe the cascaded fiber¡¦s melting surface. Then, we pair with special light source to do the examination. Thus, we can overcome the obstacle, do automatically manufacture of the cascaded fiber in a small area, and reduce the coupling loss of cascaded fiber.