The eye-safe 1550 nm all-fiber single-frequency pulsed laser has broad and attractive application prospects.The laser developed in this paper adopts all-fiber main oscillation power amplification (MOPA) structure and out-of-cavity acousto-optic modulation method.The first-stage preamplifier stage adopts 1.5 m single-mode polarization-maintaining erbium-doped fiber with the output power of 21.45 mW;the second-stage adopts 1.5 m double-clad polarization-preserving co-doped fiber with the output power of 253.6 mW;the power amplifier stage adopts 1m double-clad polarization-maintaining large-core-diameter co-doped fiber,and when the pump power is 15.9 W,the single-frequency pulsed laser output with power 2.6 W,pulse width 260 ns,and repetition rate 10 kHz,is finally realized.By optimizing the length of the gain fiber and the passive fiber at each level,the amplified spontaneous emission (ASE) and Stimulated Brillouin Scattering (SBS) are successfully suppressed,the influence of noise during the amplification process is eliminated,and the single frequency pulse characteristics with peak power up to 1 kW is obtained.