We present an all-fiber 1.94 μm nanosecond pulse laser in master oscillation-power amplifier configuration.A dualFBGs gain-switched Tm3+-doped fiber laser is built and is used as the seed laser.The output characteristics of the amplifier are studied at different pulse repetition rates,and the maximum output energy of 500 μJ is achieved under incident pump power of 39 W.The emitting spectra are checked at 5 and 10kHz,and no obvious nonlinear effects are observed in the spectrum of the amplified laser.The beam quality factor is M2 =2.1 ± 0.03 measured by the traveling knife-edge method,and the laser beam spot is also monitored by an infrared vidicon camera.