Abstract: A method making use of several times of flashes to detect the distance and luminance of a target is proposed. The method applies to an image capturing device. First, a flashlight installed in the image capturing device emits out a flash to illuminate the target. A flash response value reflected by the target is then received. Next, a distance value and a luminance value corresponding to the target are calculated according to the flash response value. Subsequently, whether the flashlight emits out a flash of an appropriate intensity is determined according to the distance value and the luminance value. If the flashlight does not emit out a flash of an appropriate intensity, the step of emitting out a flash to illuminate the target by the flashlight of the image capturing device is repeated.