The application provides a device and method for multiplying signals. The device comprises a light source, a lens group, an excitation monochromator, a cuvette, an emission monochromator, at least oneconcave mirror, an excitation light converging lens group and a signal collection lens group; the light emitted by the light source sequentially passes through the lens, the excitation monochromatorand the excitation light converging lens group, enters the cuvette to excite a fluorescence signal, and then enters a detector after passing through the signal collection lens group and the emission monochromator; and the concave mirror is arranged on a light path other than an excitation light path and a signal collection light path. By adopting the scheme of the application, the function of collecting and utilizing the excitation light and the fluorescence signal can be realized, and the problem of low utilization rate of the excitation light and limited collection of the fluorescence signalin the prior art can be solved.