A pressurized infusion device and a liquid cooling system are disclosed. The pressurized infusion device includes a liquid storage tank and a pump. The liquid storage tank has a first end and a second end opposite to the first end. The first end has a first connecting structure, and the second end has a second connecting structure. The pump is connected with the first end of the liquid storage tank and has a third connecting structure, a first connecting port, a second connecting port, a third connecting port and a fourth connecting port. The third connecting structure corresponds to the first connecting structure. A pump flow channel from the first connecting port to the second connecting port is formed inside the pump, and a bypass flow channel from the third connecting port to the fourth connecting port is also formed inside the pump.