Abstract: Effects of beforehand quenching and tempering process on microstructure and properties of DC53 die steel were studied by hardness testing and impact testing, then the fracture morphology were analyzed. The results show that lower hardness and higher impact energy could be obtained for spheroidized DC53 die steel by adding quenching and tempering treatment before final heat treatment. The proper hardness and impact toughness could be obtained after the tested steel was tempered at 400 ℃ after beforehand quenching and tempering process.