Abstract: With the miniaturization and diversification of electronic components and devices, the power density and heat flux increase rapidly during the development and iteration. That brings rising demands on highly effective heat dissipation. Focused on the problem of heat spreading, the paper gives an introduction to the basic principle of vapor chamber (VC) heat spreading technology. A specific floating heat sink with VC is tested and analyzed to compare its heat spreading performance with conventional heat sink using heat pipe. The antigravity performance is also studied and regressed in simulation. The results show that the floating heat sink with VC performs better than conventional heat sink using heat pipe in heat spreading, while its performance can be influenced by different directions of gravity. It is not recommended to use two VCs in a vertical state with one piece above another. The equivalent heat conductivity coefficient obtained from simulation can be used as a reference in future designs of related products.