Abstract: Different simulated post weld heat treatment regimes were used to heat treat 12Cr2Mo1 steel and 14Cr1Mo steel for pressure vessels. The mechanical properties and microstructure of the materials after heat treatment were analyzed using methods such as mechanical property testing and microscopic analysis. The results show that with the extension of simulated post weld heat treatment insulation time, the strength of the material significantly decreased, plasticity and toughness improved, and the change in grain size was not significant. With the extension of the simulated post weld heat treatment insulation time, the amount of carbide precipitation in the microstructure of the material increased, and the carbide aggregated and grew, resulting in weakened solid solution strengthening, dislocation strengthening, and dispersion strengthening effects, ultimately led to a decrease in the strength of the material.