In order to get excellent integrated properties of ductility and strength of DTH Bits,the microstructure and mechanical properties of steel 22SiMnCrNi2Mo with different Mn content(1.20%,1.30%,1.40%) were studied by optical microscopy,scanning electron microscopy and hardness tester.The results show that the hardness and strength of the steel increase as Mn content increasing,while the ductility and impact toughness decrease.When Mn content is about 1.30%,22SiMnCrNi2Mo has superior strength and ductility.