Abstract：Karstic collapse columns are a kind of vertical structures typically formed at Carboniferous-permian coal fields of north China and widely distributed at 45 coal mines of 20 coal fields. Through characteristics analysis of interior rock masses and exterior shape of karstic collapse columns in the coal mine areas of north China，it is concluded that there are several influence factors and dynamic geological actions on forming process of karstic collapse columns，among which karst and geological structure are the basic factors of their formation. The forming of karstic collapse columns results from repeated processes of collapse，intermission，dissolve erode，convey，subsidence，fall and so on under the dynamical action of rock mass gravity，geo-stress concentration，negative vacuum pressure and other actions on karstic cavity and groundwater violence flow. The bottom of rocks at syncline axis is tensioned and inverse cuneiform-like rock masses are formed. By contraries，cuneiform-like rock masses are formed at anticline axis under compression. So，it is propitious for whole rock mass to move down under gravity at syncline axis and karstic collapse columns are formed. The basic rule is explained in the light of mechanics，following which karstic collapse columns are more likely formed at syncline axis than at anticline axis in north China.
