The effect of plastic pre-deformation on hydrogen embrittlement of 304L austenitic stainless steel was investigated by tensile testing.A group of flat tensile specimens were firstly strained to 3%,6%,10%,15%,20% and 25% of plastic strain and then were catholically charged with hydrogen in 0.5 M H2SO4 for 96 h at a current density of 50 mA/cm2.After charging,the specimens were immediately strained again to failure.