Abstract: A light-emitting module with a focus adjusting function is described. A light-emitting module includes a light-emitting diode, a first hollow cylinder and a second hollow cylinder. A first hollow cylinder encloses the light-emitting diode and has a first thread around an outer surface thereof. A second hollow cylinder has a second thread on an inner surface thereof, wherein the first thread is meshed with the first thread such that the second hollow cylinder is telescoped from the first hollow cylinder when the second hollow cylinder rotates relative to the first hollow cylinder. An optical lens is disposed within the second hollow cylinder, wherein the optical lens moves relative to the light-emitting diode so as to adjust a projected beam's focus.