Abstract: The interconnect test and fault diagnosis for system buses are important to the manufacturing and maintenance of electronic products. The previous test algorithms which are proposed in literatures have some problems, such as existing redundant test vectors and having long test time etc. An adaptive and fast diagnosis algorithm was proposed according to the analysis of the interconnect-fault syndromes on system buses. The test process was divided into two phases. In the first phase, the short and stuck-at faults on supernets were diagnosed and then the supernets were divided into several groups according to the diagnosed short faults. In the second phase, the "parallel walking 1" test vectors were applied to the grouped supernets to diagnose the open faults. The results show that the proposed algorithm can support maximal diagnosis, remove the redundant test vectors, shorten the test time and realize fast diagnosis.