The　objective　of　this　paper　is　to　investigate　the　effect　of　spatial　dimension　of　roadside　structures　in　landscape　design.　The　method,　which　is　normally　used　in　the　architecture　and　art　design　research,　is　introduced　into　transportation　engineering.　Results　presented　indicate　that　when　roadside　structures　are　within　50　m　beside　highway,　their　dimension　is　highly　sensitive　to　highway　users;　when　structures　are　from　50　m　to　100　m　beside　highway,　people　are　relatively　sensitive　to　their　dimension;　while　the　distance　between　roadside　structure　and　highway　edge　is　beyond　100　m,　people＇s　sensitiveness　is　relatively　worse.　This　result　is　very　useful　to　control　space　form.