The utility model discloses a power transformer on-line state monitoring system base on a vibration method. The monitoring system comprises a temperature signal acquisition conditioning circuit disposed inside a transformer, an acceleration signal acquisition conditioning circuit arranged outside the transformer, a switch value acquisition conditioning circuit arranged outside the transformer, a voltage/current sampling conditioning circuit electrically connected with mutual inductors of the transformer, an A/D analog-to-digital conversion circuit, a display, a main controller and a power supply module supplying power for a whole system. The temperature signal acquisition conditioning circuit, the acceleration signal acquisition conditioning circuit, the switch value acquisition conditioning circuit and the voltage/current sampling conditioning circuit are electrically connected with the main controller through the A/D analog-to-digital conversion circuit, and the display is electrically connected with the main controller. According to the utility model, on-site parameters of the vibration, voltage, current, temperature and switch value of the transformer are detected and diagnosed on-line through sensors, so that the transformer can safely operate with high efficiency.