The invention discloses a transformer multi-parameter fault monitoring system and a detecting method. Partial discharge signals and vibration signals are respectively collected; the partial dischargesignals are combined with the vibration signals to obtain one combined signal group; amplitude limiting, filtering, and amplification are carried out on the combined signals and then over-voltage andover-current protection are carried out to obtain analog signal output results; and with one group of analog signal output results, two kinds of fault signals can be detected simultaneously. The partial discharge signals are combined with the vibration signals to obtain one combined signal group by using the signal combination technique; the partial discharge fault of the transformer and the internal vibration fault of the winding can be understood simultaneously by observing one group of signals; and the final analog signal output change can be caused no matter which signal group has a problem, so that a transformer fault result is obtained. Therefore, the detection efficiency is improved and the detection accuracy is enhanced stably. The many references are provided for the workers; andthe fault detection and maintenance pressure of the transformer are reduced substantially.