The invention relates to the technical field of heat dissipation devices, in particular to a thermosyphon heat dissipation device which comprises a condenser, an
evaporator and a gas-liquid separator. The condenser comprises a condensation body part, an inlet structure and an outlet structure, wherein the inlet structure and the outlet structure communicate with the condensation body part. The
evaporator comprises an
evaporation main body part, a liquid inlet and an air outlet, the liquid inlet and the air outlet are communicated with the
evaporation main body part, the air outlet is communicated with the inlet structure, and the liquid inlet is communicated with the outlet structure. The gas-liquid separator at least comprises a liquid collecting
pipe, the first end of the liquid collecting
pipe is communicated with the gas outlet and the inlet structure, and the second end of the liquid collecting
pipe is communicated with the liquid inlet. The gas-liquid separator is arranged so that the gas-liquid separation path can be formed between the
evaporator and the condenser, at least part of the liquid working medium in the working medium flowing out of the gas outlet can flow back into the
evaporation main body part through the liquid inlet through the liquid collecting pipe, the
dryness of the working medium entering the condenser can be improved, and the
cooling efficiency of the condenser can be improved; and therefore, the overall heat dissipation efficiency of the thermosyphon heat dissipation device can be improved.