[Purposes] Municipal solid waste incineration (MSWI) is a kind of highly dense granular material produced after domestic waste incineration. This work aims to study the strength and deformation characteristics of MSWI applied as subgrade materials. [Methods] The characteristics of MSWI are investigated by laboratory triaxial shear stress?strain test and cyclic triaxial load simulation based on discrete element PFC2D. [Findings] The mechanical characteristics of the MSWI generally meet the requirements of subgrade filling. In the triaxial shear test, the peak strength of MSWI increased with the enhancement of confining pressure; With the increase of water content, the shear strength increased at first and then decreased. The measured internal friction angle of the MSWI index is 34.75°, and the cohesion is 54.13 kPa, which meets the parameters required by subgrade materials. At the same time, based on PFC2D model, the influence of confining pressure and deviator stress on the permanent deformation of MSWI under cyclic load is analyzed. It is concluded that with the increase of confining pressure, the axial strain gradually decreases, while with the rising deviator stress, the axial strain increases gradually. [Conclusions] The application of MSWI as subgrade filling has certain feasibility, which provides a reference for further study on the engineering application of MSWI.