Abstract: Condensation is an important physical process in heat transfer equipment. Compared with the traditional single-phase flow loop, the latent heat released by the condensing phase change heat is quite large, so a very small amount of fluid flow can meet the thermal control requirements. With the continuous development of space industry, efficient thermal control technology becomes more and more important. Therefore, how to rationally use the two-phase transformation heat transfer technology must be seriously considered, and special attention must be paid to the influence of gravity on heat transfer. Traditional ground-based condensation techniques often rely on gravity to facilitate the discharge and flow of condensate, but in the weightless environment of space, these methods are no longer suitable. At present, methods such as free-fall tower drop and parabolic flight are mainly used to create microgravity environment. However, due to the short microgravity time obtained and the high cost of experiments, this study simulated different gravity conditions by centrifugal force method to study the influence of gravity, volume flow rate and tube diameter on the axial temperature change in horizontal tubes. Due to the influence of gravity conditions, the liquid will accumulate at the bottom, resulting in lower temperature of the tube wall. Through visual analysis, it can also be seen that there are wavy and spiral flow states in the tube. When gravity conditions change, the measured temperature is generally lower than that under normal gravity conditions. The deterioration of heat transfer depends on the operating conditions. The increase of steam flow rate will improve the deterioration of heat transfer, but the improvement is limited, and the overall temperature of the test section will be slightly increased. At low flow, test section temperature variations are more sensitive to gravitational conditions, while at high flow, test section temperature variations are insensitive to gravitational conditions. The above findings will help in the design and optimization of heat transfer equipment.