Abstract: Cr26 high chromium cast iron was heat treated by using different annealing processes, and the microstructure, hardness and machinability of the Cr26 high chromium cast iron were studied. The results show that the hardness of the cast high chromium cast iron is high, and the structure with pearlite as matrix can be obtained by the heat treatment process of cooling from 1020℃×2 h furnace cooling to 720℃+720℃×2 h furnace cooling to room temperature, the Rockwell hardness is reduced to 41.6 HRC, which solves the problem of damaging the tool in intermittent cutting of the high chromium cast iron.