For　cable　dome　structure,　prestressing　construction　process　is　the　change　of　the　geometrical　system　from　mechanism　to　structure　which　can　bear　design　load.　The　following　aspects　are　considered　including　the　prestressed　cable　system　setting　and　achieving　of　the　formed　shape　of　structure　by　prestress　tension,　the　formed　shape　of　structure　satisfying　normal　use　and　safety　requirements,　determining　the　reasonable　form　by　optimization　of　prestressing　degree.　Prestress　tension　form-finding　and　simulation　of　whole　loading　process　were　analyzed　through　restart　analysis　for　cable　dome　structure.　Firstly,　as　prestress　tension　methods　has　no　influence　on　the　final　formed　shape　of　structure　by　analyzing　prestress　tension　simulation　for　cable　dome　structure,　a　flexible　technical　space　will　be　created　for　construction　unit　formulating　plans　of　prestress　tension.　Secondly,　the　whole　process　simulation　under　different　prestressing　degrees　was　performed　to　obtain　performance　control　indexes　at　each　stage.　The　prestress　rationality　and　safety　of　structure　were　determined　based　on　the　conclusions　for　the　project.　At　last,　the　initial　prestressing　degree　P0　that　can　keep　the　initial　geometric　form　was　determined.　The　research　shows　that　the　initial　prestress　P0　of　7.5~10.0　times　as　the　design　prestress　is　the　safe　and　reasonable　choice　by　analyzing　the　elasto-plastic　ductile　performance　of　different　span　cable　dome　structures　under　different　prestressing　degrees.　The　research　methods　and　conclusions　was　used　in　design　of　large-span　cable　dome　structure,　which　is　roof　structure　of　the　National　Fitness　Center　in　Ejin　Horo　Banner,　Inner　Mongolia,　first　built　in　mainland　of　our　country.