Diglycidy1-4,5-epoxycyclohexane-1,2-dicarboxylate (TDE-85)/methyl tetrahydro-phthalic anhydride (MeTHPA) epoxy resin was modified by polyurethane(PU), and its structural characteristics and properties were studied by infrared spectrum analysis(IR), scanning electronic microscopy (SEM), mechanics testing and thermogravimetric analysis (TG). The results indicate that epoxy polymeric network Ⅰ and polyurethane polymeric network Ⅱ are formed in the PU-modified TDE-85/MeTHPA epoxy resin.Meanwhile the PU-modified TDE-85/MeTHPA resins have heterogeneous structure. The miscibility between epoxy (EP) and polyurethane (PU) as well as the phase size are dominantly determined by the mass fraction of polyurethane prepolymer (PUP) in the EP/PU blends. With the increase of PUP mass fraction, the tensile strength, impact strength and thermal stability of the PU-modified TDE-85/MeTHPA epoxy resin all firstly exhibit increasing tendency, and decrease after successively reaching their maxima. When the number-average molecular mass of PPG is 1 000 and the mass fraction of PUP is 15%, the tensile strength, impact strength and thermal stability of materials obtained, compared with TDE-85/MeTHPA epoxy resin, are improved obviously.