P92 heat-resistant steel was used to demonstrate that creep rupture life evaluation period could be shorted by the assistant of the creep data from short-period stress relaxation test without reducing the prediction precision. Research showed that the minimum creep rate and the relaxation creep rate were exchangeable, and the stress exponent and the apparent activation energy analysis of the constant strain creep and the constant stress creep showed a similar deformation mechanism at the condition of T and . The creep rupture life predicted through the combination of these two kinds of creep data was closer to the real creep data than that evaluated by the traditional method based on the time to rupture only, and the precision of the evaluated creep strength increased at last 14.5 %.