A distance measuring system includes a light source module, an image capturing device, a signal processing unit, a selecting unit, and a distance calculating unit. The light source module is configured for emitting a first and a second infrared light beams in an asynchronous manner. The first infrared light beam has a same intensity with the second infrared light beam. The image capturing device is configured for capturing images of the first and second infrared light beams reflected by a measurement object. The signal processing unit is configured for analyzing the images of the first and second infrared light beams reflected by the measurement object to determine intensities thereof. The selecting unit is configured for selecting one of the first and second reflected infrared light beams whichever has a greater intensity. The distance calculating unit is configured for calculating a distance to the object from to the distance measuring system.