With progress in the LED luminous efficiency, the LED gradually expands the scope of application from the backlight to general lighting. In the application of the backlight, a light guide plate (LGP) is used to guide the LED light and emits the light uniformly from its surface to achieve a uniform planar light source. Except for the merit of slim volume, the LGP can prevent the LED light from directly entering the eyes resulting in glare; thereby the LGP is also used for general lighting applications, especially for the high-directionality lighting with slim volume. For the illumination, the prescribed distribution of the light emitted from the LGP had better modulated by both the microstructure on the LGP surface and a LED lens/coupler. In general, distribution of the light emitted from the LED is partially adjusted by the LED lens/coupler before the light entering the LGP. In this study we designed a LED coupler to collocate with two types of LGPs so that the LGP can uniformly emits the highly-collimated light or the light with the prescribed intensity distribution, which can be used for the backlight or lighting application, respectively.