Abstract: The effects of austenitizing temperature and cooling method on the formation of Widmanstatten structure of 45steel were studied by heat treatment experiments with different heating temperatures and cooling rates. The results show that no Widmanstatten structure is formed in the microstructure obtained with furnace cooling, when the heating temperature is 860-1000 ℃ and the holding time is 1 h. At the same heating temperature, the Widmanstatten structure grage of air-cooled sample is higher than that of asbestos coating cooled sample. However, when the cooling rate increases to the air cooling, the Widmanstatten structure level decreases or no longer increase. At the same cooling rate, the heating temperature increases from 860 ℃ to 1000 ℃, all the obtained Widmanstatten grade shows an increasing trend.