Abstract: Hainan Island, known as China’s ‘Nanfan Silicon Valley’, is a vital tropical agricultural zone where double cropping rice predominates. However, fragmented farmland and poor soil quality in some regions have reduced yields, threatening local food security. Identifying actual and potential yield gaps in double cropping rice and proposing targeted yield-improvement measures thus hold important theoretical and practical value. This study first precisely determined the reproductive periods of double cropping rice in Hainan Island, then used the Vegetation Photosynthesis Model (VPM) to estimate actual yields for 2000, 2010, and 2020. Subsequently, potential yields were simulated with the Global Agro-Ecological Zones (GAEZ) model, enabling grid-scale comparison between actual and potential yields. Finally, tailored strategies for increasing rice production were proposed for areas with significant yield gaps. The results show that: 1) the actual yields of early rice increased in the north but decreased in the west and south, with over 95% of changes within 3000 kg/ha; late rice and all-year rice yields rose across more than 80% of the island’s area. 2) During 2000–2020, early rice consistently showed lower potential yields and production than late rice. The potential yields of all three rice types declined in most regions, especially in the north where they fell below 3000 kg/ha, while rising by 3000–6000 kg/ha across much of the west and south. 3) Significant yield gaps were observed in coastal regions, particularly in western and southern Hainan Island, where absolute yield gaps (AYG) of early and late rice exceeded 1000 kg/ha and 1500 kg/ha, respectively, and relative yield gaps (RYG) surpassed 100% in most coastal areas. 4) To narrow yield gaps in high-gap regions, spatially tailored measures were proposed, including precision water-nutrient management, wind-erosion control via shelterbelts, land consolidation into larger contiguous blocks, and policy incentives for irrigation and fertilizer support. These integrated strategies are expected to enhance rice productivity and strengthen food security in Hainan Island.