For the dimension synthesis of eight-bar linkages for 4-position, a solution region synthesis method was presented. Firstly, the solution curves meeting the requirements were obtained according to the specified 4-position 4R open chain. The solution region was set up according to feasible sections of solution curves. Secondly, the linkage with defects was removed from the solution region by using defects identification method of eight-bar linkages. Finally, the feasible solution region was built and practical engineering requirements were considered and imposed. The eight-bar linkages from the feasible solution region, which met the requirements, can be picked out rapidly and accurately by designers. The problem of dimension synthesis of eight-bar linkages for 4-position was solved effectively by the solution region synthesis method and the eight-bar linkages could be widely applied in reality. The synthesis process of eight-bar linkages for 4-position was illustrated by the example.