Epoxy/ultrahigh molecular weight polyethylene (UHMWPE) blends have been prepared by in-situ polymerization method. The effects of UHMWPE from 2.5 wt % to 10 wt % on the tensile properties of blends have been studied. Tensile properties of blends are characterized and were shown that content 10% UHMWPE was effected on performance of polymer blends significantly. Thermal characteristics of the polymer blends were determined by using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). TGA thermogram indicated that increased thermal stability of blends after incorporation of UHMWPE. The DSC was shown that Tg of polymer blends increased. The enthalpy of melting (rHm) obtained from DSC curves was increased with increase in UHMWPE content in epoxy matrix, due to depend on UHMWPE content in blend systems. The rheology of polymer was envisaged by DMA is affected on the polymer blend. The incorporation of UHMWPE increased mechanical properties of blends. Degradation kinetic parameters have been calculated for thermal degradation processes using two mathematical models namely, Coats-Redfern and Broido’s methods. Morphological behaviour of fractured blends has been studied using scanning electron microscopy (SEM).