Abstract: Factor analysis approach was used to determine the source of water inrushed to Mining Area Ⅵ-8 at Heng-yuan coal mine.An orthogonal factor-loading matrix was obtained by taking the main anions and cations dissolved in the waters sampled from the inbreakable aquifers and the inrush waters to Mining Area Ⅵ8 as the analysis targets.The analysis result shows that Factor 1 and Factor 2 denote the water in the limestone aquifer in Taiyuan Group and the other one in sandstone aquifer in the coal measure strata,respectively.The factor loadings of inrush waters to Mining Area Ⅵ-8 distributed between those of the limestone water and those of the sandstone water in a Plane Coordinate adding with the nearly perfect common variances of the three water types indicate that inrush waters to Mining Area Ⅵ-8 are the intergradations from the water in Taiyuan Group to that in coal measure strata.