For the extremely weak echo signal and the poor anti-interference ability of the long-distance laser fuze, the high signal noise ratio (SNR) receiving system based on laser coding mode was designed. In order to improve the weak signal receiving ability, the avalanche photodiode (APD) with high sensitivity, low noise and high gain was adopted. And the optimum multiplication factor of APD when the system obtains the highest SNR was analyzed and calculated. Then, the amplifying circuit optimum matching with APD and the decoding circuit were designed, and validated by the experiments. The theory and experiment results indicate that the design is efficiency and capable to the long distance laser fuze, the system can exactly decode the weak laser coding signals received and export the ignition signal.