The Split Hopkinson tensile Bar (SHTB) is one of the most widely used technique to study various material behaviors under tensile loading and high strain rate. Since stress wave propagation between incident and transmitter bar is disturbed by specimens and grips with thread, the stress-strain relation of the specimen, which is calculated from the strains of the incident and transmitter bars, may not match with the stress-strain relation measured directly from the specimen. The specimen thread pitch is optimized to obtain high measurement accuracy for the SHTB system.