Abstract: Ordinal uniaxial tensile test and room-temperature small punch test were carried out on P91 steel used in high-pressure steam conducting pipe in a power plan. The small punch tested results were calibrated through experimental calibration method and reversed finite element method, thus yield strength and tensile strength of the tested steel were got; The calibration results were compared with the results got from uniaxial tensile test. The results show that the yield strength deviation and tensile strength deviation from experiment calibration and uniaxial tensile test were 8.6% and 21%,respectively; While the yield strength deviation and tensile strength deviation from reversed finite element method and uniaxial tensile test all were -2%. Reversed finite element owns higher accuracy for calibrating small punch test results.