Overlapped time domain multi-plexing (OvTDM) is an innovative encoding scheme that can obtain high spectral efficien-cy. However, the intentional inter-symbol in-terference (ISI) caused by OvTDM will make the decoding process more complex. The computational complexity of maximum like-lihood sequence detection increases exponen-tially with the growth of spectral efficiency in OvTDM. As a consequence of high complex-ity, the decoding effort for a given spectral ef-ficiency may occasionally exceed the physical limitations of the decoder, leading inevitably to buffer overflows and information erasures. In this paper, we propose a bidirectional Viter-bi algorithm (BVA) based on the bidirectional sequence decoding for OvTDM. With the BVA, the decoding operation starts simultane-ously from the both ends of the corresponding trellis and stops at the middle of trellis. The simulation results show that compared with Viterbi algorithm (VA), the decoding time of BVA can be reduced by about half. And the memory space of two decoders in BVA are about half of that in VA, which means that the BVA has lower memory requirements for de-coder. And the decoding performance of BVA is almost the same as VA.