There is provided a mode switching method of a dual mode optical navigation device. The dual mode optical navigation device is configured to be operated on a working surface and has a first bottom surface and a second bottom surface having an included angle with the first bottom surface. The mode switching method includes: determining whether the first bottom surface or the second bottom surface contacts with the working surface; switching the dual mode optical navigation device to a first mode when identifying that the first bottom surface contacts with the working surface; and switching the dual mode optical navigation device to a second mode when identifying that the second bottom surface contacts with the working surface.