Abstract: In this paper the inflation-type vapor chamber fin applied in telecommunication base station is studied and designed innovatively. Firstly, thermal performance of the common inflation-type vapor chamber fin with beehive tube structure is simulated and analyzed using VOF model. The results show that the beehive structure vapor chamber fin has poor performance as vapor and liquid blend together in the tube, the liquid gathers at the lower part of the vapor chamber, while the gas gathers at the upper part. And the temperature at the upper part is obviously different from that at the lower part. Three types of inflation-type vapor chamber fin with cycloid curve tube structure are proposed to improve its thermal performance. The cycloid vapor chamber fin constraints the vapor and liquid flows in the designed trace, therefore less liquid gathers at the lower part and less vapor is trapped at the upper part. As a result, its heat dissipation efficiency is improved. The experimental data suggest that thermal resistance of the cycloid structure is 18% lower than that of the beehive structure. When the heat power is 30 W, the temperature of top heat source is reduced by 1.6 ℃. In a word, the new inflation-type vapor chamber fin with cycloid structure tube has better heat performance, which has the potential to provide a better thermal solution for the telecommunication base station