Biswapped network (BSN) is a new topology for interconnection networks in multiprocessor systems. BSN is built of 2n copies of an n-node basic network and total nodes are 2n 2, and its basic network may be hypercube, mesh and other networks, hence we can construct BSN-Hypercube and BSN-Mesh by using hypercube and mesh as basic network. Some topological properties of BSN have been investigated, and some algorithms have been developed on the BSN such as sorting and matrix multiplication etc. In this paper, we discuss the fault tolerant issue of the BSN including network connectivity and fault diameter.