Abstract: An optical device with switchable multiple lenses can be mounted on an electronic device through a connecting module, and provides finely-adjusted alignment with an image capturing lens in any position, and provides a zoom or wide-angle lens for the user to change the focal length and view field of the image. A light-filling/polarizing regulation module to fill light and eliminate unnecessary reflected light to avoid marginal diminishing effect of the image. The optical device includes a viewing device, a connecting module and a light-filling/polarizing regulation module, wherein the viewing device includes a lens module located in the housing and having at least two lenses through which an image captured by the image capturing lens is magnified. At least two lenses has the same lens power, or at least two lenses of different magnifications can be used with the switchable lens seat to obtain the effects of switching different lenses.