The pulsed fiber amplifier is provided with design optimization adapted to the characteristics of different pulse signals, thus satisfying the needs of various applications. The operating wavelengths cover 1.0um, 1.5um and 2.0um, this pulsed fiber amplifier is capable of amplifying ultra-short pulses (picosecond and femtosecond pulses) without pulse distortion, and achieving high power amplification of short pulses at nanosecond level or long pulses from hundreds nanosecond level to microsecond level.