In response to the issues of unstable liquid level, overflow of shell side fluid from weir plates, and dry burning of heat exchange tubes caused by wind, waves, and sloshing in conventional reboilers on FPSOs, we focus the study on the debutanizer tower reboiler in the light hydrocarbon recovery and treatment process of the South China Sea Liuhua 16-2 oilfield group FPSO. We aim to optimize and design the internal structure of the reboiler by analyzing the sloshing characteristics of the FPSO hull. Additionally, we use FLUENT software to compare and analyze the liquid level stability of the pre-optimized and post-optimized reboilers under vessel sloshing conditions. The specific approach to optimizing the structure of the reboiler includes adjusting the size of the weir plate, adding wave-shield baffle plates, rear baffles, and discharge bottom plates. The simulation results show that when the reboiler tilts, the liquid phase overflow from the shell side of the optimized reboiler to the other side of the weir plate is significantly reduced compared to the reboiler before structural optimization. Moreover, the liquid level of the reboiler can return to stability after 20 seconds with structural optimization, while the reboiler without structural optimization takes 36 seconds to return to stability. This study provides reference for the design of reboilers under sloshing conditions.