A light projecting apparatus of a scanner module and a method for arranging the light sources thereof are provided. The light projecting module includes a substrate with a first end, a second end and a middle section. The first end and the second end are respectively positioned at both sides of the middle section. The light projecting module also includes multiple light emitting diodes (LEDs) positioned on the substrate. An arrangement spacing interval is formed between every two adjacent light emitting diodes; the arrangement spacing intervals are respectively decreased gradually from the middle section toward both the first end and the second end.