Abstract: Under cantilever bend loading,a test method of several-grade nominal strain to control surface crack front strain was adopted and low cycle fatigue surface crack propagation rate test of 10CrNiMo structural steel were performed with and without zero adjustion of residual strain when one grade nominal strain altered to another higher one.The test results were compared and analyzed and it manifested that residual strain will retard surface crack propagation rate,the higher residual stain,the more obvious this effect;the quicker surface crack propagation rate will appear when one grade nominal strain altered to another higher one with residual stain zeroed.The reason for the above phenomenon was analyzed and discussed.