Polystyrene/Styrene-Ethylene-Propylene-Styrene/Vinyl Ester Resin (PS/SEPS/VER) blends used as matrix of ultra high molecular weight polyethylene (UHMWPE) fiber-reinforced composites, which included both physical crosslinking points of thermoplastic resin SEPS and chemical crosslinking network of thermosetting resin PS/VER, were prepared by solution blending and hot-molding. Morphology and mechanical properties of the PS/SEPS/VER composites were investigated in this work. The microstructure of PS/SEPS/VER composites observed by means of scanning electron microscopy (SEM) was correlated with mechanical properties. It is worth noting that, stiffness increased sharply with the addition of VER within a certain range. Impact properties verified the structure that the physical crosslinking points of SEPS were immersed in the chemical crosslinking network of PS/VER. Dynamic mechanical analysis revealed that, incorporation of VER changed the storage modulus and loss tangent. In brief, addition of VER had improved mechanical properties, thermal stability, and fluidity of the composites during processing, indicating a successful result for preparing resin matrix material with outstanding comprehensive performances. Analog map was presented to facilitate better understanding of the special structure of PS/SEPS/VER. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 119: 93-101, 2011