Abstract: 3Cr17 mold steel has excellent mechanical properties.The lack of control on the process design and components results in a higher uneven level of carbide， poor shape and segregation， which influence the process performance and usability performance of steel.Through the research on 3Cr17 mold steel carbide segregation， it puts forward a plan that heating it 1h at 940±10 ℃， doing fast oil cooling twice， and then incubating in 730 ℃ 2～3 h， then cooling with the furnace.