Abstract: Different annealing temperature and annealing time were adopted for annealing treatment of M2-1.0Si silicone modified M2 high speed steel.Through the test and analysis of the microstructure and high temperature mechanical properties,it is found that the annealing temperature and annealing time had important influence on the microstructure and mechanical properties of silicone modified M2 high speed steel.Too high annealing temperature and too long annealing time were not suitable.When at a given annealing time of 8hours,with the increase of annealing temperature from 760℃ to 760℃,the average grain size of M2-1.0Si silicone modified M2 high speed steel firstly remained basically unchanged and then increased dramatically.Both the tensile strength and percentage reduction of area first increased then decreased.When at a given annealing temperature of 850℃,with the extension of annealing time from 4 h to 12 h,the average grain size of silicone modified M2 high speed steel increased sharply after slowly increased,tensile strength and percentage reduction of area decreased sharply after basically remained unchanged.Optimum annealing temperature of M2-1.0Si silicone modified M2 high speed steel is 850℃,the annealing time is 8 h.