With　the　development　of　computer　aided　design　technique,3D　reconstruction　from　2D　input　has　been　widely　used　in　the　research　of　computer　vision.　Plentiful　works　have　been　done　in　three　orthographic　views,　in　this　paper　a　new　method　is　introduced　under　single　2D　input.　The　system　in　this　paper　aims　at　the　reconstruction　of　useful　objects　in　computer　design.　Angle　histogram　and　corner　detector　are　used　in　this　system　to　extract　feature　and　size　the　object　respectively,　then　GA-BP　neural　network　is　used　to　deal　with　the　relationship　between　the　featuresand　3D　objects.　This　system　is　developed　on　the　basis　of　Microsoft　Foundation　Classes　and　Open　Inventor　5.0　by　Mercury.　Examples　and　experimental　results　are　shown　in　this　paper.©　2010　IEEE.