In order to find out the water quality of Digou coal mining subsidence area in Huainan, water samples were collected and tested to analyze the characteristics of surface water. The test water area was divided into three zones, i.e., Jihe river (J), subsidence ponding area (C) and control area (D), then its surface water quality was assessed using single factor and comprehensive water quality identification index method based on the water samples from these different zones. The results show that both the Jihe river and subsidence ponding area are weakly alkaline water bodies with relatively clear water quality and good transparency. The highest concentrations of TN and NH+4 both occurred in Jihe, which is attributed to the agricultural pollution of non point source in the periphery. Heavy metals of Cu, Zn, Pb and As were all enriched to some extent in the subsidence ponding area, which is related to the leaching and releasing of heavy metals from coal gangue, the emission of automobile exhaust and the fugitive dust on the surface. Samples from the sample points of C1, C2 and C3 in the the subsidence ponding area, which is 15 m apart from each other and further away from Jihe river, were collected and analyzed. It is found that the concentrations of TN and NH+4 decreased with the distance to Jihe River, whereas the heay metals showed the opposite. The results of single factor water quality identification index show that the pollution of Hg and CODMn are more severe in the subsidence ponding area and Jihe River than the other pollutants. However the water quality index Pi of the three zones all comply to the standard of Class III according to the comprehensive water quality identification index. In the intersection of water bodies, the water quality of sample points of J3, J4 in Jihe River and C1,C2 in the subsidence ponding area ranked as follows: J3（2.320）