The utility model discloses a test platform of a transformer station capacitive device on-line monitoring system constituted by a resistor, a capacitor, a multi-throw rotary type change-over switch, a sampling resistor, and a fuse. The test platform can be used to solve the test problem of the transformer station capacitive device on-line monitoring system. According to the utility model, the transformer station capacitive device can be accurately simulated, and the test platform can be used to change the dielectric loss value of the capacitive device by adjusting the resistance value, therefore the accuracy of the on-line monitoring system can be verified, and the reliable platform can be provided for the test of the on-line capacitive device on-line monitoring system.