Sandwich composites suffer from delamination damages under bending， shear， impact and other loads. The degree of delamination damage is closely related to the fracture toughness of type Ⅰ and type Ⅱ. Due to the introduction of ring fiber bundles in its thickness direction， the binding ability of the ring fabric with the core layer is enhanced， which makes it excellent in anti-delamination performance. In this paper， the fracture toughness of type Ⅰ/Ⅱ interface of fabric foam sandwich composites is studied. According to the test standard， the plain weave fabric foam sandwich composite and the loop fabric foam sandwich composite are made seperately. The toughening mechanism is studied by the double cantilever beam （DCB） test and the end notch flexure （ENF） test. The results show that the interfacial properties are greatly improved by the introduction of annular fiber bundles. Compared with the plain weave structure， the typeⅠfracture toughness G_ⅠC and typeⅡfracture toughness G_ⅡC of the loop structure are increased by 434% and 400%， respectively. A DCB finite element model is established and the cohesive force model is used to describe the crack propagation. The numerical results agree well with the experimental results. The finite element model is applied to the study of DCB specimens with different initial crack lengths， which provides a reference for the design of composite materials.