The utility model provides a power supply monitoring device for power to each fan of transformer in the transformer substation is monitored, the wireless transmitting device be connected including a plurality of current detection device that set up respectively on each fan and power connecting wire, a plurality of and current detection device one -to -one, setting are at the wireless receiving of distal end device and the display device that is connected with the wireless receiving device, and display device is according to each current detection device 0's of wireless receiving device received signal display state. The utility model discloses it is simply directly perceived, can accurately fix a position the fan that the power supply trouble appears, need not the artifical investigation of participating in to the scene, reduction time, cost of labor improve work efficiency.