The invention discloses a flywheel energy storing system of a diesel locomotive. A central control unit of the diesel locomotive sends a working command to the flywheel energy storing system; an energy system of the diesel locomotive stores spare energy to the flywheel energy storing system; and the energy system of the diesel locomotive and the flywheel energy storing system provide energy for the loading of the diesel locomotive. The flywheel energy storing system disclosed by the invention has the advantages that the multifunctional energy storing system of the diesel locomotive is high in energy storing capacity; the efficiency is high, and can reach 90% or above; the charging time is short, and is almost free from being influenced by external environment; the cycle life is almost unlimited; and the requirements for maintenance and servicing are low, so that the energy utilization of the diesel locomotive is reasonable.