This paper presented the effect of constituent materials on impact damage and strength reduction of sandwich structure, composed of laminated woven E-glass facesheets and polypropylene thermoplastic honeycomb core. Effect of low-velocity impact was the main interest in a variety of layered configurations. Compression after impact (CAI) has been carried out to determine the residual strength of impacted sandwich structures. Three different thicknesses of core of 20, 40 and 60mm subjected to three different levels of impact energy of 15, 30 and 45J were investigated. Impact response of the panel was recorded and analyzed in terms of peak load, indentation, energy absorbed and time. A profile analysis using optical 3D surfaces profiler was carried out to attain the indentation depth and damage area of the samples. The tested samples were then sectioned into halves to capture the failure mode or damaged sequence of the polypropylene thermoplastic honeycomb core. The dominant failure modes of the core indicated that polypropylene thermoplastic honeycomb core is a high strength material which can absorb higher impact energy and retain a higher degree of structural integrity.