Abstract: Mountains are complex ecological systems, with unique structures and functions, and have rich biodiversity, water and mineral resources, and opportunities for tourism. Mountain ecology is the study of mountain structures, functions, and processes, as well as the exploration, sustainable utilization and conservation of mountain resources. In this paper, we review the effects of major topographic elements on ecological factors, summarize the ecological benefits of mountains, and discuss the current research issues and topics for Mountain Ecology. It is emphasized that in topography of mountainous areas is the most critical controlling factor for ecological structures, functions, and processes. Topography affects the abundance and distribution of organisms by modifying solar radiation, heat, moisture, soil and fertility. For this reason, topography and topographyinduced ecological phenomena and processes are considered to be the most critical topics in mountain ecology. Topographic research addresses such issues as ecological complexity, biodiversity, mountain climate changes, mountain ecological engineering, mountain sustainable development, and quantification of topographic elements (elevation, slope, aspect, and location). Among these, developing appropriate methods for quantifying topographic elements is a key technique. We also suggest a need for a synthetic study of relationships between humans and the natural world based mountain sustainable development.