Ecosystem service spatial flow is the delivery of an ecosystem service to people or the movement of material and people. Its assessment elucidates the dominant contributors of ecosystem services and their spatial relationships. In this study, we defined a concept of regional correlation degree as the flow quantity of ecosystem services from a supply area to a demand area, which can be used as an important reference for regional ecological compensation. Based on the characteristics of wind direction and spatial location in the Beijing-Tianjin sandstorm control engineering area, this study developed a regional correlation model with the provision degree and influencing degree of sand-fixing services. Subsequently, we estimated the sand-fixing services in the sandstorm control engineering area in 2015 by the revised wind erosion equation (RWEQ), and analyzed the ecological links between different administrative districts of the sandstorm control engineering area and Beijing Municipality. The results indicate that the regional correlation degrees of sand-fixing services ranged from 0 to 13.43%. Chicheng County in Zhangjiakou City presented the highest correlation degree with Beijing, and the high correlation zones of sand-fixing services were Sunnitezuo Banner, Xuanhua District, Huaian County, Xiahuayuan District, and Suniteyou Banner. However, Wengniute Banner, Chengde County, Ningcheng County, Jixian County, and Yangyuan County showed the lowest ecological links with Beijing in sand-fixing services. The regional correlation of sand-fixing services was generally high in the west and low in the east. This phenomenon mainly can be attributed to the predominant wind direction in the Beijing-Tianjin sandstorm control engineering area, and the spatial heterogeneities of sand-fixing services. Additionally, the social and economic development levels in different districts presented negative correlation with the correlation degree of sand-fixing services. This result implies that the regions of higher correlation degree of sand-fixing services with Beijing were suffering from more severe poverty. Therefore, we concluded that Beijing should pay more ecological compensation to those counties with high correlation degrees in sand-fixing services to ensure the sustainable provision of sand-fixing services.