We report an all-fiber two-stage high power pulsed amplifier,seeded with a 1550nm,1 kHz repetition rate rectangular pulse,and based on Er/Yb co-doped double clad fiber.All the characteristics are measured in the experiment.The maxima/slope efficiency is 22.56%,which is the highest we know of at such a low repetition rate,and the maximal output signal power is 1W.The various factors that affect the pulsed amplifier performance are analyzed.A high output power while keeping high power conversion efficiency can be obtained with careful selection of the input power,pump power and repetition rate.The experimental results show that the crucial parameters should be optimized when designing all-fiber pulsed amplifiers.