High power continuous green lasers have important applications in laser displaying, biomedicine, non-ferrous metal processing, and other fields. These research issues have become hot topics in the laser field. Therefore, to achieve high power and high efficiency continuous green laser output, a high-power fiber laser is built by using a narrow-band fiber grating, and the frequency doubling technology is studied by using the laser as the fundamental laser source. The fundamental frequency fiber laser with a bandwidth less than 50 pm is obtained, and the output power can reach 100 W. Based on this fundamental frequency laser, 532 nm green laser output of 11.6 W is achieved by using a one-way frequency doubling KTP crystal, and the frequency doubling efficiency is 11.6%. Linearly polarized laser is obtained by polarizing the fundamental frequency laser with a polarizing prism. The frequency doubling experiment of p-polarized laser passing through a polarizing prism is carried out. The output power of 532 nm frequency doubling laser is 7.3 W and the frequency doubling efficiency is 14.2%. These experiments show that the frequency doubling efficiency of fiber lasers can be improved by controlling the spectral bandwidth of fundamental frequency laser via the narrow linewidth grating. The 532 nm green laser can be obtained by doubling the frequency of the s-polarized laser reflected by the polarizing prism. The green laser power can be increased to more than 14 W by combining two green laser beams via the laser beam combination technology.