A fault-tolerant unit and a fault-tolerant method for through-silicon via (TSV) are provided. The fault-tolerant unit includes TSV structures TSV1˜TSVn, nodes N11˜N1n, nodes N21˜N2n and a switching module. The TSV structure TSVi is connected between the node N11 of the first chip and the node N2i of the second chip, wherein 1≦i≦n. The switching module is connected between the nodes N21˜N2n of the second chip and a test path of the second chip. In normal operation state, the switching module disconnects the test path and the nodes N21˜N2n when the TSV structures TSV1˜TSVn are valid. The switching module connects the node N2i to at least another one of the nodes N21˜N2n when the TSV structure TSVi is faulty in the normal operation state. In test status, the switching module connects the test path to the nodes N21˜N2n.