The Nd3+-doped pulse polarization-maintaining fiber laser pumped by 808nm semiconductor laser is investigated experimentally and theoretically. The wave form of output pulse was detected by a TDS5104 oscillograph，and the spectrogram of the output pulse was obtained by using a spectrum analysis apparatus. Originally，the single pulse energy of 2.3mJ with average power of 2.55W was generated at the repetition rate of 1kHz. By changing the resonance cavity and making other modificantions of the laser, we obtained the highest single pulse energy of 3.3mJ with peak power of 17.9kW at the repetition rate of 1kHz，and the pulse width was 184ns and the average power of the output pulse was 3.5W.