The present invention relates to a heterogeneous polyimide-supported transition metal complex catalyst for epoxidation of olefin, which is prepared by impregnating a heat- and acid-resistant polyimide resin with a homogeneous metal catalyst of molybdenum, vanadium, tungsten or titanium, and a process for preparing epoxy compounds using the same. The heterogeneous polyimide-supported transition metal complex catalyst of the invention provides superior catalytic activity, selectivity and stability in the epoxidation of higher olefin. Further, the catalyst of the invention has strong resistance against heat and acid. Besides, the catalyst of the invention may provide the following advantages which are critical in industrial use: it permits relatively high yield of epoxy compounds; and, it can be easily separated from the reaction product, which eases recycling of the catalyst.