An optical distribution design method based on azimuth modulation is put forward. Model OSLON SX high power Light Emitted Diodes (LED) are chosen as a light source. An optical model of a 4×4 LED array is built with 16 LEDs. The illumination distribution on the receiving surface is controlled by changing the azimuth of each row of LEDs. The research result show that the illumination distribution on the receiving surface is most uniform when the upper and lower portions of the LED array tilt at an angle of ±30° respectively.