The study on microstructure properties of 12% Cr martensite heat-resisting steel with different heat treatment process shows that the microstructure of said steel after heat treatment proces of normalizing(1 020～1 070 ℃×1 h) + tempering(760 ℃×2 h) or high-temperature annealing(1 050 ℃×1 h) + tempering(760 ℃×2 h) is lath-shaped martensite

and its hardness is in the range of standard;while after heat treatment process of isotermal annealing(1 050 ℃×1 h→670 ℃

750 ℃

870 ℃) +tempering(760 ℃×2 h)

the microstructure of said steel is lath-shaped matensite + pearlite

and its hardness is also in the range of standard;the microstructure of said steel after heat treatment process of not fully annealing(850 ℃

870 ℃) has two regions with different colors

in which the dark-colored region is granular pearlite

the light-colored region is ferrite + carbide

and the hardness of speciemens is less than the lower limit required in standard.