Abstract: As a porous medium, rocks have permeation effects. Elastic-plastic theory and damage mechanics are used to obtain the stress distribution of rocks around wellbore. With dynamic discriminant, strict stable conditions for wellbore are put forward, and critical stress values of wellbore are acquired take into account the permeable effect. When the stress of wellbore is close to critical loads, wellbore is in the state of instability, and when dynamic disturbance is present, wellbore will collapse because of instability.