Previous research showed that integrating phase change materials with solar tubes stabilizes heat transfer fluid temperature, but the low conductivity of phase change materials limits solar tube performance. Although studies on fluid properties and heat transfer behavior are extensive, the critical influences of fin shapes' effect are limited. This paper introduces an innovative design: an all-glass vacuum tube with a solar salt sleeve surrounded by outer fins. Numerical simulations compare heat transfer dynamics of straight rectangular, circular, and trapezoidal fins. The study examines how these shapes affect temperature field evolution and phase transition. Results indicate: 1) Fins reduce temperature disparity between solar salt and heat transfer fluid, with rectangular fins showing the greatest improvement of only 12oC. 2) Fins accelerate salt phase transition, albeit with a slight delay in initiation. Adding trapezoidal ring fins reduces the complete phase change duration by 5 minutes. 3) the tube with 4 rectangular fins demonstrates the highest temperature field and maximum total heat storage of 269kJ, highlighting its superiority.