The utilization of high-quality curing agents to improve loess filler can not only use local materials to cut down the project cost, but also diminishes the amount of traditional binders such as lime and cement, which is of great significance for carbon reduction. In order to explore the mechanical properties and durability of composite improved loess using CG-2 curing agent and cement, a series of tests are conducted, including triaxial shear tests, unconfined compressive strength (UCS) tests, freeze-thaw cycle tests, and water stability tests. Furthermore, the microscopic pore structure of the composite improved loess is studied by SEM NMR and XRD tests. The findings indicate that the maximum dry density and optimal water content of the composite improved loess show a trend of increasing first and then decreasing with the increase of cement and curing agent dosage (DCA), and the maximum value is obtained when a cement dosage is 6 % and a DCA of 0.020 %. The shear strength and UCS of the composite improved loess are significantly higher than those of the cement improved loess (CIL), and the greater the amount of curing agent, the higher the strength. On the premise of reaching the same strength standard, the addition of curing agent can significantly reduce the amount of cement. With the increase of the DCA and cement dosage, the durability of composite improved loess is significantly improved than that of the CIL. The addition of curing agent can also reduce the spacing of mineral crystal planes of the composite improved loess, enhance the cementation characteristics of soil particles, change the contact mode between particles, and then improve the physical and mechanical properties of the improved soil. It is recommended to use a cement dosage of 6 % and a DCA of 0.020 % for the improvement of loess filling materials of secondary and below highway base, which can achieve the optimal improvement effect.

来源平台：CONSTRUCTION AND BUILDING MATERIALS