Polyimide fiber /epoxy paper-based composite materials were prepared from polyimide chopped fibers and polyimide fibrid fibers by means of wet papermaking combined with hot pressing and resin impregnation,and the effects of hot-pressing temperature,hot-pressing pressure and epoxy resin impregnation increment on the properties of polyimide fiber paper-based composite materials were investigated.The results show that ( 1) after the hot pressing,the contact area of polyimide fibers increases,which results in the improvement of mechanical and electrical properties of the polyimide fiber paper; ( 2) resin impregnation further improves the mechanical and electrical properties of polyimide fiber paper-based composite,concretely,the tensile index increases by 1. 25 fold and the dielectric strength increases by 17%; and ( 3) at a hot-pressing temperature of 210 ℃,a hot-pressing pressure of 120 N/mm and an impregnation increment of 20%,the composite possesses good mechanical and electrical properties,namely a tensile index of 57. 5 N·m/g,a tear index of 6. 86 mN·m2 /g and a dielectric strength of 12. 3 kV/mm,which means that the composite is potentially useful in such fields as aerospace,insulation barrier and environmental protection.