In order to solve the problem, such as high melting point of Yb3+/Al3+ co-doped silica glass and being difficult to be prepared, the Yb3+/Al3+ co-doped silica glass is prepared by the powder melting technology based on the high-frequency plasma and the related theory and technology are researched. The technology provides the possibility to fabricate very large and multicore rare earth doped photonic crystal fiber (PCF), and single or multiple kinds of rare earth ion doping can be realized. The bubble in the glass is eliminated and the reduction of Yb3+ ion is inhibited by adding auxiliary heating device and using oxygen as the melting atmosphere, respectively. The Yb3+/Al3+ co-doped PCF is drawn by the stack and draw technology using the glass as the PCF core. The background attenuation value of the PCF at 1200 nm is less than 0.25 dB/m, and the laser is emitted in the laser system by using the PCF as the gain medium. The test results indicate that the Yb3+/Al3+ co-doped silica glass prepared by the technology has good optical properties.