A liquid cooling device, which is used for performing heat dissipation to switching chips and optical modules in the electronic device, and comprises: a first cooling plate attached to the switching chip and used for performing heat dissipation to the switching chip; a second cooling plate attached to the optical module and used for performing heat dissipation to the optical module; an air-liquid heat exchanger used for containing cooling liquid and performing cooling to backflow cooling liquid through cooling air; a transmission pipe used for sequentially transmitting the cooling liquid flowing out from the air-liquid heat exchanger to the first cooling plate and the second cooling plate, which then flows back to the air-liquid heat exchanger; and a power device used for controlling the cooling liquid in the transmission pipe to be sequentially transmitted to the first cooling plate and the second plate and then flow back.