Abstract: According to GB/T 228. 1-2010 measurement method of elongation after fracture, BW300TP wear-resistant steel plate with small plastic surplus was selected for tensile test, and the reasons for the difference of elongation after fracture measured by machine-measured method and hand-measured method were analyzed, and some suggestions for revising the standard were put forward. The results show that the elongation after fracture measured by machine was less than that measured by hand because the fracture position deviated from the center of gauge length. The formula y=0. 850 5x+5. 183 8 could be used to compensate and correct the elongation after fracture. It is suggested that the minimum parallel length of P7 lead sample in GB/T 228. 1-2010 be modified to 60 mm, cancel the stipulation of parallel length of non-proportional sample with rectangular section in Appendix D L_c≥L₀+1. 5 √S₀, and add the correction method and recommended value of elongation after fracture for machine-measured of different test materials.