A server device includes a casing, an electronic assembly, a cover, and a heat dissipation device. The electronic assembly includes a circuit board and at least one heat source. The circuit board is disposed on the casing, and the heat source is disposed on the circuit board. The cover is removably disposed on the casing. The heat dissipation device includes at least one air cooling heat exchanger and at least one liquid cooling heat exchanger. The air cooling heat exchanger is fixed on and thermally coupled with the heat source. The liquid cooling heat exchanger is fixed on the cover and thermally coupled with the air cooling heat exchanger.