Abstract: This study investigate the permutation flowshop scheduling problem in which there are sequence dependent setup times on each machine, commonly known as the SDST flowshop. The optimization criteria considered is the minimization of the makespan or Cmax. Many heuristics and meta-heuristics have been successfully applied to this kind of problem before like genetic algorithm, tabu search and greedy algorithm and the objective of this study is to assess their effectiveness in a more realistic and complex environment. We present a hybrid electromagnetism-like (HEM) algorithm for the permutation flowshop scheduling with sequence dependent setup times that have shown superior performance against other meta-heuristics when applied to proposed problem. The proposed HEM algorithm benefits of a new concept named priority assigning to calculate electrostatic force and also it implements a new formulation for solution charge. Using a good approach for acquiring the initial solutions and also some effective local searches to finding neighborhood solutions are other novelties of the HEM. For evaluating the proposed algorithm we have coded several well-known algorithms for SDST flowshop. All methods including HEM are tested on the randomly instances and results indicate that HEM is very competitive with the existing best-performing algorithms.