[Objective] The resilience and coordination degree of the social-ecological-economic system of five cities in the mountainous areas of northern Guangdong Province were measured to provide a theoretical basis for the sustainable development of underdeveloped areas.[Methods] From the perspective of resilience, this study constructed a theoretical framework and evaluation method of the social-ecological-economic coupling system, and established binary and ternary coordination-degree models.[Results] ① The resilience of the social-economic-ecological system generally increased; the resilience of the social and economic subsystems increased relatively slowly, whereas the resilience of the ecological subsystem decreased. ② The resilience level of the social-economic-ecological system was obvious. For example, the resilience level of the social subsystem increased, and exhibited the characteristics of being high in the surrounding areas and low in the central area. In contrast, the resilience level of the economic system exhibited a downward trend, and was high in the east and low in the west. ③ The ecological-economic system was on the verge of maladjustment, the social-ecological system was basically coordinated, and the social-economic system was primary coordinated; hence, the social-ecological-economic system was in the stage of slight maladjustment.[Conclusion] The resilience of the coupling system in Northern Guangdong Province needs to be improved, especially with respect to the ecosystem. In the future, close attention should be given to the coordination and interaction of the social-ecological-economic system in Northern Guangdong Province.