It is important for maintaining the safe operation of power transformer to monitor the states of transformer winding on the real-time basis. The winding’s states can be reflected by its vibration signal, which can be measured by the accelerometers located on the transformer tank. In a short-circuit experiments for one large power transformer, the state of winding of every phase can be initially detected by the change of transformer vibration intensity for every short-circuit shock. The method of time-frequency analysis is further used to analyze the shock signal in order to confirm the winding’s states. Compared with the traditional method based on short-circuit reactance measurement, the time-frequency analysis can exactly show the fault characteristics of the winding.