An optical mouse and image capture chip thereof. The image capture chip comprises an image sensor, a calculating logic circuit, and a refreshing logic circuit. The image sensor has a plurality of sensor units, capturing an image according to an exposure parameter to provide a plurality of exposure values. The calculating logic circuit provides an average exposure value by calculating the exposure values. If the exposure sample is within a first exposure range, the refreshing logic circuit maintains the exposure parameter and accordingly drives the image sensor to capture a next image. If the average exposure value is within a second exposure range, the refreshing logic circuit adjusts the exposure parameter with a first exposure extreme and accordingly drives the image sensor to capture a next image. If the average exposure value is within a third exposure range, the refreshing logic circuit adjusts the exposure parameter with a second exposure extreme and accordingly drives the image sensor to capture a next image.