According to light-emitting diode (LED) light source’s characteristic and the principles of non-imaging optics, a simple computation method is proposed which can control light path through adjusting the direction component of free-form surface. Some reflectors suitable for different application were designed by this algorithm which based on a single LED light source. Then optical entity was imported into TracePro software for non-sequential ray tracing. As a result of simulation, the optical system achieves uniform illumination. This algorithm brings a new idea for non-imaging design. It’s suitable to design microscope lighting and projection display that require high uniform lighting system.