Abstract: After carburizing treatment, 18Cr2Ni4WA steel exhibits high surface hardness and good core load bearing capacity, making it widely used in key components such as heavy load transmission gears. The traditional carburizing process at 930 ℃ has the problems of long production cycle and high energy consumption. High temperature carburizing significantly improves carburizing efficiency of steel, but it also tends to cause an increase in retained austenite content and an imbalance in carbide morphology, thereby weakening the mechanical properties of the carburized layer. To address these issues, this study adopted a high temperature carburizing process at 950 ℃ and systematically investigated its effect on the microstructure evolution and strength-ductility matching of the carburized layer in 18Cr2Ni4WA steel by adjusting the secondary quenching temperature of 775, 800, 825, 850 ℃. The results show that as the secondary quenching temperature increases, the prior austenite grain size grows from 7.05 μm to 12.58 μm, the size of martensite structural units delimited by high angle grain boundaries （i.e., the effective grain size of martensite） increases from 1.53 μm to 2.18 μm, and the retained austenite volume fraction in the carburized layer rises from 8.6% to 12.1%. Under the secondary quenching condition at 775 ℃, continuous network carbides exist in the carburized layer, which easily induce intergranular cracking. When the quenching temperature is raised to 800 ℃, the continuity of the network carbides is effectively broken, significantly improving the ductility of the material. In contrast, further increasing the quenching temperature leads to grain coarsening and an increase in retained austenite, resulting in a marked decrease in the elongation of the material. Based on comprehensive microstructure and property analysis, the sample quenched at 800 ℃ achieves the best strength-ductility matching, with a fracture elongation of 4.6% and a strength-ductility product of 7.5 GPa·%. These findings provide an experimental basis for optimizing the subsequent heat treatment process of high-temperature carburized 18Cr2Ni4WA steel.