Open-cast coal mining in China has developed rapidly due to its obvious advantages over underground mining. However, it may have negative ecological effects, such as biodiversity loss, water shortage, and soil erosion. Identifying and protecting the key areas with high importance for ecological sustainability are great challenges. The construction of an ecological security pattern (ESP) can improve landscape connectivity and reduce the fragmentation of ecological patches. Thus, it can be seen as an effective measure to protect regional ecological sustainability. In this study, taking the Pingshuo open-cast mining area as a case study area, ecological sources are identified through ecosystem structure and function, and corridors are extracted by constructing an ecological resistance surface, thus forming a valid ecological network. The results show that in 2018, the ESP in the study area included 11 sources with an area of 147.74 km² and 17 corridors with a length of 92.11 km. Specifically, the ecological sources are mainly distributed in Taocun Township, Jingping Township, and Xiangyangbao Township. Among these 11 sources, sources 7 and 8 are reclaimed waste dump land, meaning that the land reclamation work in Pingshuo greatly promotes connectivity. Furthermore, dump 1 can be restored in the future by constructing three new corridors, which will greatly improve the landscape connectivity of Yuling Township. Overall, this study not only provides an effective framework for constructing and optimizing ESPs in ecologically fragile coal mining areas, but it also adds new insights to the concept of land reclamation in these areas.