Abstract: Induced polarization(IP) method can obtain different response characteristics in detecting coal goafs, goaf water accumulation areas, fissure water areas etc, has a good distinguishing effect. Predecessors have conducted a lot of research on the detection mechanism of IP, but most of them are analyzed from the physicalelectrical characteristics of the method itself. By combining the physical-electrical characteristics of IP with the theory of soil mechanics, a theoretical analysis of the different characteristics of the IP to detect coal goaf wateretc from the "three-phases" was carried out. Experiments of the relationship between relevant parameters of "threephases" (saturation, porosity) and the IP characteristics (apparent resistivity, polarizability) were conducted. The theoretical analysis and experimental results show that the IP characteristics of coal goaf are of "high resistivity, low polarizability", the goaf water accumulation areas appears as "low resistivity, medium-high polarizability", and the fissure water areas appears as "low resistivity, high polarizability"; the IP characteristics of coal goaf water are closely related to the changes of saturation and porosity. An engineering example of a coal mine in Shanxi Jincheng verified the theoretical analysis results.