In this paper, we searched the parameter of BEF (Brightness enhancement film) using commercial FRED server for backlight module. The pattern analysis was carried out to understand its characteristic. The current structures used in LCD backlight are double-layer BEF. In addition, BEF of 3M takes the lion¡¦s share. But this may increase the thickness and cost of backlight module. In order to avoid those disadvantages, we tried to design single-layer BEF and characterize the effect through parameters study by using FRED software simulation. pyramid-shaped microlens array of BEF was constructed. Therefore, the effect of the variation of the structure parameters can be analyzed, such as prismatic degree (£c), prismatic structure on the brightness enhancement. It can be found from the result of simulation that the changes of the prismatic degree (£c) of 85 degree influence the brightness enhancement the most.