Time series motifs are previously unknown,frequently occurring pattes in time series or approximately repeated subsequences that are very similar to each other.There are two issues in time series motifs discovery,the deficiency of the definition of K-motifs given by Linet al.(2002) and the large computation time for extracting motifs.In this paper,we propose a relatively comprehensive definition of K-motifs to obtain more valuable motifs.To minimize the computation time as much as possible,we extend the triangular inequality pruning method to avoid unnecessary operations and calculations,and propose an optimized matrix structure to produce the candidate motifs almost immediately.Results of two experiments on three time series datasets show that our motifs discovery algorithm is feasible and efficient.