Engineering challenges related to saline soil roadbed disaster prevention and mitigation, land resources, protection of stone relics, geothermal development, carbon dioxide geological storage, and nuclear waste disposal recently have become increasingly prominent. A critical factor in addressing these issues is understanding the coupling theory of thermal and salt diffusion in rock and soil. This theory is essential for preventing soil salinization, preventing diseases of infrastructure and stone relics, enhancing heat extraction efficiency, improving sealing effectiveness, and reducing groundwater pollution. This paper first summarizes the research methods related to thermohaline double diffusion coupling in both soil and rock. The paper then systematically reviews typical theoretical models in this field. Building on this foundation, the paper explores the future research directions for thermohaline double diffusion coupling theory, particularly in the context of modern energy demands and environmental protection needs. Comparative analyses of different thermohaline diffusion coupling models are also presented. Finally, the importance of studying the coupling theory of thermohaline diffusion in rock fissures is highlighted, especially in relation to critical engineering problems such as CO2 storage in saline aquifers, geothermal exploitation in salt zones, and nuclear waste disposal in salt caverns. Additionally, the paper outlines future research prospects for the coupling of thermohaline diffusion with mechanical effects in the context of soil and rock conservation, particularly for the preservation of cultural relics.