Abstract: Selecting Hengyuan Coal Mine as research object, the paper quantitatively evaluated the complexity of the mine structure through fractal dimension in fractal theory，and analyzed coupling relationship between structural complexity and mine inrush. The paper evaluated mine floor water inrush in Hengyuan No.6 Coal Mine with fuzzy comprehensive method, divided and forecasted water inrush risk region.The results show that mine structure is more complicated in general, the fractal dimension value of the region reaches 1.31, but the complexity of mine structures have obvious nonuniformity，the greater of the fractal dimension is, the more complicated of the structure is, and the distribution of water inrush points are more intensive; the fuzzy evaluation result shows that most of No.6 coal seam floor has high water invasion criticality; more dangerous and dangerous area accounts for 47%; grade classification of floor water inrush conforms to reality; most of the water inrush points which are in the middle of the mine are more dangerous or dangerous zone.