The invention provides a power supply structure of a desktop computer, a mainboard to which the desktop computer belongs comprises a mainboard power input port. The power supply structure comprises a cabinet, a power supply device, a power adapting device and a mainboard power supply line. The cabinet comprises a cabinet inner space and a bearing plate. The cabinet inner space is divided into a mainboard mounting side provided for the mainboard to be disposed thereon and a back side. The bearing plate comprises a first through hole. The power adapting device is disposed in the cabinet and located at the back side. The power adapting device comprises a power source input port and a mainboard power supply port penetrating through the first through hole. The mainboard power supply line is connected with the mainboard power supply port and the mainboard power input port.