Abstract: Polyimide (PI) has been widely used due to its excellent mechanical properties and thermal stability. However, its inherently low thermal conductivity, high-temperature creep behavior, and limited tribological performance restrict its application under demanding conditions. In this study, delaminated d-Ti₃C₂T_x MXene nanosheets were synthesized via selective etching and exfoliation of the Ti₃AlC₂ MAX phase, and their structural characteristics were analyzed. These nanosheets were then incorporated into the PI matrix via in situ polymerization to fabricate d-Ti₃C₂T_x/PI composite films. The incorporation of MXene constructs effective thermal conduction pathways within the polymer, significantly enhancing the composite's thermal conductivity-up to an eightfold increase compared to pure PI at a filler loading of 5wt%. The rigid layered structure of MXene improves the storage modulus and high-temperature creep resistance of the composite, especially at 300℃. Furthermore, during the friction process, MXene facilitates the formation of a stable transfer film on the contact surface, reducing the coefficient of friction (COF) by approximately 8.3% compared to pure PI. Compared with conventional inorganic fillers, MXene exhibits superior dispersibility and reinforcement efficiency. This work systematically evaluates the multifunctional reinforcement effects of MXene in PI composites and proposes a dual enhancement mechanism based on thermal conduction network construction and tribological interfacial regulation, providing both theoretical insight and practical guidance for the development of high-performance PI-based composites.