An optical navigation device includes a light source, an image sensor, a navigation unit and a lift detection unit. The light source is configured to illuminate a work surface. The image sensor receives reflected light from the work surface to output an image frame. The navigation unit is configured to filter the image frame and output a filtered image frame. The lift detection unit is configured to calculate a maximum difference of intensities between two adjacent pixels in the image frame, calculate a pixel number of pixels of interest in the filtered image frame, and identify a lift event by comparing the maximum difference with a difference threshold and/or comparing the pixel number with an operating threshold.