A spectrum stabilizing method used for a radial detection spectrometer comprises the steps of (1) acquiring an environment background energy spectrum, (2) comparing the acquired environment background energy spectrum with a standard environment background energy spectrum, and (3) conducting scaling on the radial detection spectrometer if the difference between the acquired environment background energy spectrum and the standard environment background energy spectrum is larger than a predetermined threshold value. According to the spectrum stabilizing method, online spectrum stabilization of the radial detection spectrometer can be achieved conveniently and fast.