The　structural　synthesis　is　the　primary　and　the　most　important　issue　in　the　process　of　mechanism　creative　design.　In　the　paper,　Firstly,　select　a　1T　symmetric　parallel　mechanism,　and　the　constraint　and　mobility　of　the　branches　can　be　analyzed.　With　the　method　of　linear　combination　of　the　screws,　the　new　branches　are　constructed.　Then,　using　the　measure　of　separation　and　merger,　parts　of　the　limbs　of　the　parallel　mechanism　can　be　replaced　by　equivalent　coupled　structures,　so　corresponding　symmetric　coupling　mechanisms　with　equal　mobility　are　synthesized.　Finally,　solving　the　constraint　screws　of　the　branch　of　the　coupling　mechanism,　in　order　to　prove　the　hybrid　mechanism　is　full-cycle　or　not.　©　(2014)　Trans　Tech　Publications,　Switzerland.