未來液晶顯示器產品對於高色彩品質、產品壽命、快速啟動、低電壓驅動光源等特性的需求之下，面板廠商們開始思考CCFL(冷陰極燈管)的可替代光源方案，而LED(發光二極體)是現階段最被看好的下一世紀背光模組光源。 LED使用於背光模組光源上，目前市面上產品已常見應用於側光式背光模組(如：手機螢幕、PDA及NB)，至於LED應用在直下式光源設計上，因LED光具指向性及點光源之特性，引發輝度、色度不均及模組厚度不易薄型化…等設計瓶頸問題，故尚未普及。本論文研究的重點在於利用TracePro光學模擬軟體，進行直下式LED背光模組模擬、分析並設計出LED LENS結構，使光經由此LENS結構，將光線均勻分佈於背光模組空腔之中達到模組輝度與色彩均勻化及同時可達到厚度薄型化的目的。 For Liquid crystal display (LCD) products that under the needing of characteristics try to get high colors quality, life of products, fast booting and low voltage driven. The manufacturer begins to ponder the substituting light source over the scheme of Cold Cathode Fluorescent Lamps (CCFL), and LED is the most favored use as light sources to next century’s backlight. LED is use on backlight source module and often seen it applied in Edge lighting module already (screen of mobile phone, PDA and NB for example). As for LED applied in direct-lighting module design which because of LED with directed light and pointed light characters, raise the bottleneck problem of design can’t achieve color with uniform and the thin thickness of module not easily , so not popularize it until now. This thesis’s research point is use TracePro optical simulation software to execute the simulation of direct-lighting module, analysis and design the best LED Lens structure, through this structure to make light with an even distribute on chamber of backlight module, then achieve the goal that module’s luminance and color even distribution and get thin thickness at same time.