In this paper, a high-efficiency fused taper side pump coupler with pump coupling efficiency of 82%, signal light passing rate of 98%, signal input and pump input isolation of 33 dB and pump light reverse isolation of 24 dB was achieved by using the pump fiber pre pulling method. The coupler was applied to a self-made 20 W pulse laser, and a stable laser output with a peak power of 7 kW was achieved. The results show that the fused taper fiber side pumped coupler has a good application prospect in high power fiber lasers and fiber amplifiers.