For current light source of projectorUHP lamp, the disadvantages of short lifetime, high colour temperature, having harmful light, high heat density etc., restrict the application of projector in home entertainment. Recent development of LED provides the possibility of LED being a substitute light source of UHP lamp. A LED-based lighting unit composed of a LED, a collimating lens, a front fly-lens and a back fly-lens is brought forward. Several such lighting units make a basic lighting system of projector. The divergence angle of light beam from LED is compressed by collimator lens. Then the light beam is divided into several tiny light beams by the front fly-lens, and each tiny light beam will be converged to micro-display panel by converging lens. So, the light energy is gathered and the light field is redistributed. The requirements of projector on light flux and homogeneity could be met. The back fly-lens is used to match with following optical elements. As an application of the lighting unit, a signal panel liquid crystal on silicon projector is analyzed.