Abstract: The strip Wongawilli Mining method is a new type of high-efficiency subsidence reduction mining method in China,which is of great significance for reducing the damage of overburden rock,controlling surface subsidence and reducing the damage of mining to surface structures. The coal pillar is the key to control subsidence by Strip Wongawil- li mining. In order to study the coal pillar characteristics and the interaction mechanism between coal pillar system and roof in strip Wongawilli mining,the Wangtaipu mine was taken as geological model. Theoretical analysis,similar simu- lation and site measurement were combined to build a systematic model in strip Wongawilli mining. The failure characteristics of coal pillars in Strip Wongawilli mining were observed,and the mechanical structure model of strip coal pil- lar and irregular coal pillar were set up. Then the roof abscission layer and coal pillar stress and support strength were analyzed. The results show that the strip Wongawilli mining method is a special pillar system formed by narrow pillars, irregular pillars and strip pillars. The narrow pillars play a temporary supporting role. With the advance of coal mining face,the narrow pillars lose their supporting capacity after mining or in a short time,irregular pillars can play a certain role in the support of roof,and strip pillars are the key of the whole pillar system. In strip Wongawilli mining,direct roof separates from main roof,and direct roof bends and subsides to form two kinds of structures,one is to bend down to form a clamped beam,and the other is to form a cantilever structure,which applying force to strip Wongawilli coal pillars. The strip coal pillars are similar to the traditional strip coal pillars,supporting the direct roof and the old roof. The irregular coal pillars are similar to the form of supporting monomers ( similar to monomers) passively supporting direct roof. If irregular coal pillars fail,the abrupt change of compression of strip coal pillars will increase sharply, which will affect the stability of the whole strip Wongawilli mining pillar system