Abstract: Based on the basic theory of econiche, a concept of econiche of mountain settlement was proposed.The econiche of a mountain settlement may reflect spatial position of the settlement vertically along the mountain and resources space available to the settlement for sustenance, and meanwhile a mathematical model was established for calculating widths of the econiches of the 12 settlements in Shangxiameng Valley of the Zagunao Section of the Min River . Results show that in calculating widths of settlement niches, natural factors arewere the major ones to take into account, which arewere followed by economic and then social factors. Settlements with an elevation of 1900-2600m were 0.03 - 0,11 in econiche width and those with an elevation of >2600-3100m were 0.12-0.13, demonstrating that econiche width increasesd with elevation. The findings of the study may provide a new method for evaluating the relationship between people and land in mountainous regions and space planning of settlements.