Abstract: The internationally prevailing method for testing yield strength of linepipe-purpose steel involves measuring the total elongation strength R_t0.5.The causes for the error of R_t0.5 measurement of the linepipe-purpose steel are analyzed, and accordingly, methods to mitigate the said error are proposed, including well controlling the machining accuracy of the test piece, selecting appropriate loading speed, removing the adverse effect by the unevenness of the test piece by means of repeatedly leveling and "pre-loading", and properly fixing the test piece and the extension device, etc.The application result shows that these methods are capable of accurately measuring the value of R_t0.5.