The invention relates to the field of mobile communication and aims at providing a self-excitation forecasting and fast-recovery method for a digital repeater. Compared with the conventional wireless repeater application technology, the method comprises the steps of sending a GMS (globalization management system) transmission signal of a digital baseband to a cost function calculating module; calculating a signal characteristic cost function according to the signal; and carrying out characteristic function calculation on the GMS transmission signal of the digital baseband by using methods of power statistics, amplitude statistics, power spectrum statistics and training sequence statistics in the processing of carrying out self-excitation preventing on the GMS transmission signal of the digital baseband according to a characteristic cost function. According to the method, signal states can be estimated comprehensively by using a plurality of methods, and a power spectrum is judged according to the characteristic of a GSM transmission frequency spectrum, so that the influence of non-coherent jamming signals on system judgment can be prevented. Therefore, indexes on judging speed by self-excitation, misjudgment by jamming and the like can be improved.