The invention relates to a device and method for preventing a wireless while-drilling clinometer from falling into a well. According to the technical scheme, a body is provided with a plurality of grooves for assembling a plurality of sets of friction pieces and push plates in a matched mode; a mandrel is installed in an inner hole of the body, grooves are formed in the lower portion of the mandrel, and press rods are arranged in the grooves and fixed to the corresponding push plates through pins; small springs are installed in push plate grooves and provide radial centripetal force for the push plates; and one ends of reset springs make contact with the mandrel, and the other ends of the reset springs make contact with the inner end face of the body. The device and method have the beneficial effects that the mechanics principle is adopted for converting the direction and amplifying force, of the self weight of the clinometer, acted on the press rods, the friction force between the friction pieces and the inner wall of a non-magnetic drill collar is far greater than the self weight of the clinometer, and it is guaranteed that the wireless while-drilling clinometer does not fall into the well when a directional sub female cap thread is fractured; and the device is convenient to detach, same parts can be interchanged, and the operating cost of the device is lowered.