Abstract: In order to improve the thermal properties and impact rupture strength, flexural strength and hardness et al mechanical properties of polyimide (PI), two-dimensional layered structure nanomaterial Ti₃C₂T_x was prepared by liquid-phase etching of a ternary layered ceramic Ti₃AlC₂. The crystal structure and morphology of as-prepared were characterized by XRD and FESEM. The Ti₃C₂T_x/PI composites with different concentrations of Ti₃C₂T_x were prepared by wet ball milling and hot pressing. The effects of Ti₃C₂T_x on the thermal properties, impact rupture strength, flexural strength and hardness of Ti₃C₂T_x/PI composites were investigated. Simultaneously, the fracture morphology was analyzed. The results suggest that Ti₃C₂T_x with a thickness of 20-50 nm is nanosheets layered structure, which can uniformly disperse in the PI matrix. During the curing process, PI enters the Ti₃C₂T_x layers and improves the bonding force between PI and Ti₃C₂T_x, resulting in good combining interface. The addition of Ti₃C₂T_x nanosheets enhance the glass transition temperature of PI and improve the impact rupture strength, flexural strength, and hardness properties of the matrix. When adding amount of Ti₃C₂T_x is 0.25wt%, the glass transition temperature of Ti₃C₂T_x/PI composite increases by 17℃ and the impact rupture strength ascends by 31%.