The fiber-based amplification of a commercially packaged,fiber pigtailed pulsed diode laser operating at wavelength of 1 064 nm (bandwidth of 0.45 nm) was reported.The cascaded Yb-doped fiber amplifier could operate safely by using cascaded fused wavelength division multiplexing (WDM) in each single-mode amplification stage.The total isolation of cascaded WDM could protect the laser diodes from being destroyed by feedback of pump/signal power.At repetition rate of 50 kHz,pulse duration of 20 ns and average power of 0.5 mW,output power up to 0.6 W and peak power up to 600 W were obtained,with a high signal to noise ratio of 30 dB.The gain of the whole system is 30.8 dB and pulse distortion is not been observed.