Abstract: The ecological critical portion that controls the diffusion of mining interference have an important significance in maintaining the safety of ecosystem.Taking a typical mining city of Daye city as a case，and under the support of GIS，the Mining Interference Diffusion′s Resistance (MIDR) model is constructed to quantify the influencing power of the mining enterprise，disturbance sources-mining enterprises and make detailed analysis of the composition and mechanism about the resistance according to the principle of minimum cumulative resistance model.Then，the spatial identification of ecological critical portion in a typical mining city was finally realized，and its spatial distribution and regularity was analyzed.The results show that：the ecological critical portion account for 23% of Daye′s land area which consists of the majority of major mine zone，ecological sensitive area and environmental fragile zone.These ecological critical portions are closely related to the balance of the environment and the quality of original ecological environment.And it′s a better way to limit the expansion of mining activities′ disturbances and achieve sustainable development by strengthening supervision measures in these ecological critical portions.

Key words: Mining disturbances, Positional critical portion, Minimum cumulative resistance, GIS, Mining city