The invention provides a multi-mode viterbi decoding apparatus and a decoding method thereof. The decoding apparatus comprises an input data storage module, a branch path metric module, a mode selection module, a parallel add-compare-select module, a residual path storage module, a backtracking module and a sequential control module, wherein the parallel add-compare-select module is used for performing accumulative calculation on the metric values and branch path metric values of corresponding states according to a state transfer graph for obtaining accumulative values, and sending residual path selection results to the residual path storage module by taking the greatest accumulative value as the new metric value of a next state until data to be decoded ends; and the backtracking module is used for selecting different backtracking modes according to different encoding modes, and begins backtracking from any a state or the state corresponding to the greatest accumulative value so as to obtain decoding results according to the residual path selection results stored by the residual path storage module. By using the multi-mode viterbi decoding apparatus and the decoding method thereof, enormous resources can be shared, design can be optimized, and the decoding throughput can be improved.