The invention discloses a pressure maintaining device of a ladle rotary hydraulic system of a continuous casting machine, and belongs to the technical field of hydraulic equipment of continuous casting machines. According to the technical scheme, one end of a large-flow oil supply pipeline is connected with an oil pipeline of a hydraulic pump of a ladle turret , the other end of the large-flow oilsupply pipeline is connected with a ladle lifting hydraulic device and a tundish lifting hydraulic device, the large-flow oil supply pipeline is connected with one end of a constant-pressure oil supply pipeline through a pressure-stabilizing isolation unit, the other end of the constant-pressure oil supply pipeline is connected with a ladle nozzle hydraulic device and a ladle turret rotary hydraulic device, the large-flow oil supply pipeline is connected with a plurality of bag-type accumulator units in parallel, and a plurality of piston-type accumulator units are connected in parallel on the constant-pressure oil supply pipeline. According to the pressure maintaining device, the hydraulic devices, with different pressure requirements, of the ladle turret are supplied with oil correspondingly through the bag-type accumulators and the piston-type accumulators, the respective advantages are exerted, the emergency treatment of the hydraulic devices in a power outage state is ensured, the production accidents are avoided, and smooth production and safe production is guaranteed.