Traditional　structural　design　emphasizes　checking　whether　a　loaded　structure　satisfies　design　requirements　without　considering　the　construction　process.　There　is　a　great　difference　in　structures　between　the　states　in　construction　processes　and　design,　however.　To　solve　the　above　problems,　a　method　of　nonlinear　time-varying　mechanics　was　adopted　to　analyze　the　construction　process　of　a　structure.　The　structural　characteristics　in　each　construction　stage　were　analyzed　by　time-varying　mechanics　and　the　variations　of　internal　force　and　displacements　obtained.　We　conclude　that　designs　will　not　be　safe　if　the　time　varying　effect　in　the　construction　process　analysis　is　not　considered.　We　offer　advice　on　the　design　and　construction　of　large-span　structures.