Aim to calculate the limit load of pressure vessel containing volume defect under high temperature,the numerical method for limit load,which is defined as the load-carrying capacity after the structure serviced for a certain time,of 2.25Cr-1Mo steel pressure vessel structures at 873 K is proposed in the present paper.The Norton creep behavior with Kachanov-Rabotnov damage law is implemented in ABAQUS via subroutines,and the effect of creep time to the material properties of 2.25Cr-1Mo steel has also been considered.190 examples for the different sizes of volume defects of pressure vessels have been calculated.The results showed that the failure mode of the pressure vessel depends on the size of the volume defect,and the service life of the pressure vessel structure at high temperature shows the sensibility to the defect ratio.