The invention discloses a special photovoltaic power supply device for railway freight. The special photovoltaic power supply device for railway freight comprises solar batteries installed on the top surface and the side surface at the outer part of a freight train; the solar batteries are connected with a phosphorus lithium battery pack and charge for the phosphorus lithium battery pack; the phosphorus lithium battery pack is connected with a big dipper satellite information device on the freight train, and provides a power source for the big dipper satellite information device. The special photovoltaic power supply device for railway freight, which is disclosed by the invention, is reasonable in structure, and is good in operation performance; trains are charged in running through the photovoltaic charge mode without manual charge.