With the use of pulsed pumping, an optical fiber amplifier with all-fiber structure is developed based on the fused tapered fiber combiner and Yb+{3+}-doped double cladding fiber (YDCF). From the experimental results, 47-dBm peak power and 100-ns pulse duration are obtained when the repetition rate of pumping pulses is 100 Hz. The gain of the amplifier is up to 30 dB. It is shown that due to the use of pulsed pumping, pump light emits only when the signal light reaches the amplifier and thus the amplified spontaneous emission (ASE) is significantly suppressed.