Abstract: For selection of mining methods aiming at seams of different complexity, it is very important to quantitatively analyze the influence of geologic and structural conditions on coal seam complexity, and to quantitatively evaluate the complexity of seams. The paper, through analysis and determination of the influencing factors of seam complexity, put forward the concept of coal seam complexity, and reclassified quantitatively coal seams according to the complexity of coal seams. Evaluation index system of coal seam complexity was established by using multilevel quantitative analysis of geological structure. Model of coal seam complexity was built on the basis of fuzzy mathematics, and the analytic hierarchy process was applied to determine weight of the evaluation index. The fuzzy synthetic evaluation method of the coal complexity was established, and the quantitative assessment of coal seam complexity was realized.