Abstract: A rubber tyred gantry crane three-power hybrid energy saving system comprising a system controller; a unidirectional AC/DC converter; a small diesel generator set having its output going to the unidirectional AC/DC converter and supplying power to a direct-current bus after rectification; a unidirectional DC/AC inverter power supply having its input end connected in parallel with the direct-current bus, and having output going to the auxiliary transformer after inversion; a battery set and its management system; an interconnection switch; a large diesel generator set; and an auxiliary transformer. Electrical equipment mainly includes a hoist frequency converter, a trolley frequency converter, a gantry frequency converter, auxiliary electrical equipment and a control power supply.