Abstract: The coal resource of northwestern China is generally characterized by shallow depth and thicker seam. The coal seam roof has been affected by water from the surface, eolian sand, bedrock weathering zone, etc. Research of water abundance analysis on this relatively complicated aquifer system is not well enough by far. To make a synthetic evaluation for the water abundance of this area, this paper combined the particular geological situation with Ordos Zhuanlongwan Coal Mine and chose the thickness of Quaternary system sand layer, weathering zone above bedrock, coring rate, unit-inflow values and osmotic coefficient values, sandstone proportionality coefficient, landform distribution and lithology distribution as the affecting factors of Quaternary and bedrock weathering zone roof phreatic water abundance. With the calculation of ArcGIS, water abundance is evaluated through FAHP. The water abundance standard of mining area is divided with grey relational analysis into: weak, medium, relatively rich. And by this standard, the threshold value to divide water abundance is also confirmed objectively. Results showed that the relatively rich area of phreatic aquifer water abundance obtained by FAHP-GRA can mainly match with the drainage holes which have large water yield. And it verified the accuracy of this model in evaluating synthetical water abundance of coal mine.