Sandwich structures are consisted of two thin skins with high mechanical properties and a thick core with lower mechanical properties and weight. Due to high strength/ stiffness to weight ratio, these structures are used extensively in engineering structures such as aerospace structures, ship hulls, turbines blades, etc. Skin/core debonding is one of the major failure modes in these structures. In this paper, debonding resistance of sandwich panels with composite skins and a core consisted of PVC foam and a corrugated composite laminate is investigated both experimentally and numerically. Square geometry is considered for corrugated composite laminate and obtained results are compared with reference specimen with simple core made of PVC foam. The three point bend test with attached ENS fixture is used to perform the standard experimental test. The results have shown that in square specimen with 3 and 6 layer skin before the separation between skin/core, the specimens are failed from the middle of the upper skin, but for 8 layer skin, the skin/core debonding are accured before other modes of failure. The maximum skin/core debonding resistance for square specimen are increased 269.26 percent. Specimens are modeled in Abaqus and results show a reasonable agreement between experimental and numerical result.