Abstract: As a large number of deep and long tunnel is being constructed,the geostress effects and especially the high geostress effects to surrounding rock classification becomes more and more challenging. at present,the common surrounding rock classification method is to select a few indicators,then to assign some values,then to make relevant classifications.Some surrounding rock classification method cannot flexibly choose the rock classification geological indexes.Some classification indexes can influence each other.The surrounding rock classification is a complicated problem of conflicting.The extension theory methods can be used to translate the conflicting problem into the exclusive problem.This method is worthy for exploration and use.This paper combines the extension theory methods with the surrounding rock classification for high geostress tunnel.It establishes the method of rock classification for high geostress tunnel based on extension theory.The method mainly t selects the important parameters of rock classification indices that can reflect and embody the featureuniaxial compressive strength Rc,RQD index,the index Kv of rockmass integrity,index of groundwater state.It especially considers the important index with geostress.It then bases on matter-element theory,extension set and dependent function calculation to establish the material element model of the surrounding rock classification.It follows the degree of association calculations for the actual rock classification.The final rock classification can determined.the paper applies the method to actual cases.