The weld,heat affected zone and microstructure and properties of P92 steel under different heat treatment were studied. The results show that the tensile fractures of all the specimens are located in the non-weld zone,and the tensile properties at the weld are better than those in the parent metal zone.After the sample being kept warm below 700 ℃ for 60 min,the hardness of the weld is higher than t hat of the parent metal,where the hardness of the weld is between 35～45 HRC and the hardness of the parent metal is around 20 HRC. This postweld heat treatment does not improve the hardness of the weld zone.After the postweld heat treatment with heat preservation at 760 ℃for 90 min,the weld microstructure is close to the original parent material micro-structure,which is tempered tortoise,the microstructure is uniform and small,the hardness of weld microstructure decreases and is close to that of the base metal,which is the best postweld heat treatment process in the test.