An optical navigation chip. The optical navigation chip is appropriate for an optical pointing device and used for calculating a displacement of the optical navigation chip relative to an operating surface. The optical navigation chip comprises a photo sensor array driven by a photo sensor control circuit for detecting an image of the operating surface, a signal readout circuit coupled with the photo sensor array for reading out the image in analog format, an analog-to-digital conversion (ADC) circuit coupled with the signal readout circuit for converting the image from analog format to digital format, an image qualification circuit coupled with the ADC circuit for determining quality of the image and outputting a quality index accordingly, and a motion detection circuit for outputting the displacement according to the quality index.