Abstract: To explore the mechanical mechanism of deformation and instability of equal-spacing anchor roadway, taking 2^# return air uphill in S6 mining area of Changcun Mine as research subject, based on the investigation of its engineering geological condition, a mechanical model of floor with equal spacing anchor roadway was established; the mechanism of buckling of layered floor is analyzed by mechanics theory, and the criterion of mechanics is established. With the aid of the proposed mechanical criterion, the stability of No.2 return air uphill floor in S6 mining area is judged and evaluated mechanically, and the rock strata that are the first to fail and lead to support system failure are obtained.