Abstract: After forging and heat treatment, the hardness of the turbine blade for aero engine were studied and the result shows that the hardness is lower than the standard value. A series of measures were taken like regulating Cr and Ni content, gradually increasing the heat treatment temperature. The measures of adjusting the δ-ferrite content were proposed. At the same time, related mechanical tests were carried out on the heated bars with different ferritic contents. The results show that the low hardness of the leaf is related to the relatively high δ-ferrite in the material. The δ-ferrite content in 1Cr17Ni2 can be controlled by adjusting the content of Cr and Ni and quenching temperature. When the content of ferrite forming elements in raw materials is high, the δ-ferrite content increases rapidly with the increase of quenching temperature, especially when the quenching temperature is higher than 1150 ℃. When the δ-ferrite content in 1Cr17Ni2 alloy steel is too high, the mechanical properties such as tensile strength, impact toughness and hardness will be reduced after heat treatment. By adjusting the content of Cr and Ni in raw materials and choosing proper heat treatment temperature, the δ-ferrite content can be effectively reduced and the mechanical properties of parts can be improved.