An immersion cooling system includes a first casing, a plurality of fins, a liquid-cooled pipeline, and a liquid-cooled system. The first casing is used for containing a dielectric liquid in which a heat-generating component is immersed. The plurality of fins are disposed on and located outside the first casing. The liquid-cooled pipeline containing a coolant is attached to the first casing. The liquid-cooled system is disposed outside the first casing and connected with the liquid-cooled pipeline to remove heat from the coolant in the liquid-cooled pipeline. The immersion cooling system dissipates heat through two heat exchange mechanisms, that is, natural convection heat loss and heat absorption by liquid cooling.