Abstract: The effects of different solution treatment temperatures on the microstructure and properties of hyper duplex stainless steel CD3 MWN are studied. The results show that there are a lot of precipitated phases in the as cast steel. Sigma phase cannot be completely eliminated at 1 060℃. When the solution temperatures are between 1 080~1 120℃, the ferrite content can reach 55%~57%. When the solution temperature increases from 1 060℃ to 1 100℃, the tensile strength and hardness decrease gradually, and the impact performance improves gradually. When the solution temperature increases from 1 100℃ to 1 140℃, the tensile strength and hardness increase gradually, and the impact performance decreases gradually. The pitting and crevice corrosion resistance of CD3 MWN steel is better than those of CD3 MN and CN7 MS steel.