The　hollow　steel　tubes　of　concrete　filled　steel　tube　(CFST)　structure　suffer　construction　loads　during　construction　as　they　play　the　role　of　formwork.　The　steel　tubes　suffer　initial　stress　before　they　can　work　together　with　concrete　infilled.　On　the　other　hand,　they　are　also　subjected　to　horizontal　hydrostatic　loads　of　wet　concrete　as　well　as　axial　loads　during　concrete　pouring.　This　paper　deals　with　the　two　stages　design　of　CFST,　and　discusses　the　design　method.　The　idea　of　considering　construction　stage　which　is　not　included　in　existing　design　codes.　It　is　possible　to　solve　the　problem　by　finite　element　method.