The invention discloses an emergency hydraulic system of a center hydraulic transmission hydraulic lifting harrow thickener. The series problems caused by power failure of the thickener are solved. The emergency hydraulic system is characterized in that a hydraulic bottom plate block is arranged, a low pressure overflow valve, a high pressure safety valve, a reversing valve I, a throttling valve, a one-way valve II, a pressure reducing valve and a reversing valve II are arranged on the hydraulic bottom plate block, and a hydraulic motor, a one-way throttling valve, an oil cylinder, an electromagnetic ball valve II, an oil return oil filter, an energy accumulator inlet one-way valve, a hydraulic energy accumulator, a pressure detector, a nonelectric lifting harrow electromagnetic ball valve, a manual stop valve, a pressure gauge, a pressure sensor, a nonelectric lifting harrow ball valve connecting emergency power supply and the like are respectively connected through pipelines. According to the emergency hydraulic system of the center hydraulic transmission hydraulic lifting harrow thickener, high pressure oil is stored through the hydraulic energy accumulator, the high pressure oil is released during power failure, and nonelectric automatic harrow lifting is achieved. The emergency power sully is used, so that the nonelectric lifting harrow electromagnetic ball valve is in a normally-closed state and is opened when sudden power failure happens, the nonelectric lifting harrow electromagnetic ball valve is opened by the emergency power supply, the high pressure oil is made to automatically enter an oil cylinder lifting harrow, and the facts that materials press the harrow and a pool is cleared are avoided.