The invention provides a self-adaptive compensation device for a distribution transformer. The structure of the self-adaptive compensation device is simplified, the cost is reduced, and the reactive power compensation accuracy is improved. A high-voltage side of the distribution transformer is connected with a high-voltage power grid, the low-voltage side of the distribution transformer is connected with a load, and the self-adaptive compensation device is connected between the distribution transformer and the load; and the self-adaptive compensation device comprises a central control unit, a five-level two-bridge-arm inverter and a current collector, and the central control unit collects three-phase current data of the load through the current collector and outputs signals of current in phase opposite to that of reactive currents of the distribution transformer through the five-level two-bridge-arm inverter so as to offset the reactive currents. According to the self-adaptive compensation device, the five-level two-bridge-arm inverter and a conventional capacitor are combined, so that the capacity of the self-adaptive compensation device is increased; and at the same time, reactive power can be compensated accurately, the cost is relatively lower, and the self-adaptive compensation device is applicable to occasions with medium and low voltage and high power.