In the visible light communication system, the light source has a double function of illumination and communication. As the size of the room and the indoor environment is different, it is inevitable that there will be somewhere with less light irradiation or the light is weak. These places are likely to become a communication blindzone, which will greatly affect the quality of the communication. In order to solve the shadow effect, a rational layout of the light source is needed. Based on 4 m×4 m×3 m room model, four LED array was adopted as indoor lighting. A single LED light source was considered as a lambert illuminant, which obeyed the Lamber tradiation model. Through formula and software simulation analysis, it was known that when the size of LED array was 9×9 and the distance from LED array to the edge of roof was 0.4 m and the spacing between the LED light source was 0.03 m, the illumination distribution was most uniform in the horizontal plane of 2.25 m from the roof on the premise of meeting the international standard of indoor lighting. And the uniformity of illumination is 90.4% in the 4 m×4 m receiving plane. The model of layout of light source array can be extended to any size of the room in this paper, which provides a feasible solution for the layout of the indoor office lighting source.