Coastal areas are rich in resources, economically developed, and densely populated. Affected by climate changes and human activities, regional geological disasters are prone to occur and are widely distributed, especially chain disasters triggered by the continuous evolution of individual disasters, posing a great threat to coastal stability and safety of coastal cities. This study analyzes the current status of typical geological hazards such as coastal erosion, shallow gas activities, and offshore submarine landslides in coastal areas worldwide, and sorts out their concepts, distribution, failure mechanisms, and prevention measures. Additionally, it summarizes the major monitoring techniques, theoretical methods, physical models, and numerical simulation methods for geological hazard research, and explores their applicable conditions and development bottlenecks. It is found that coastal erosion, shallow gas activities, and offshore submarine landslides mostly occur in the same area, and have correlations in terms of source and causal chains; that is, continuous coastal erosion can cause shallow gas leakage or directly lead to submarine landslides, and large amount of shallow gas leakage in geological layers can also trigger submarine landslides. To prevent and control the geological hazard chain in coastal areas, this study proposes a development strategy for future geological hazard monitoring and early warning, suggesting to build a space-air-Earth-sea multi-dimension integrated monitoring system, carry out mechanism analysis of big data and numerical simulation, and improve the early warning and forecasting of disaster chains with artificial intelligence, so as to provide a reference for urban safety and geological hazard source control in coastal areas.