The regular hybrid flow shop scheduling problem, with m stages, identical parallel machines and makespan minimization, is investigated and served as the natural starting point for the hybrid flow shop scheduling problems. Some properties of this scheduling problem were discussed, and they lead to the theoretical foundation and instruction for algorithm design. Based on the active scheduling technique and reversibility property, a genetic algorithm with direction selection combined with extended Giffler & Thompson algorithm was developed. The experimental results of benchmark problems and comparisons with two other algorithms indicate the effectiveness of the proposed algorithm.