The space power system, centered around space nuclear power technology, has emerged as one of the most promising power systems for the future due to its excellent radiation resistance, compact design, long lifespan, and lightweight advantages. This study addresses the boiling heat transfer problem of liquid metal in a vertical pipe, employing the lattice Boltzmann model and introducing the Li method to adjust the surface tension. It further investigates the boiling heat transfer of liquid metal under different gravitational conditions. The results indicate that gravity has a significant impact on heat transfer performance, as gravity increases, the heat transfer capability of the liquid metal gradually enhances.