Abstract: The occurrence and mechanics of joint generally determines the integrity of rock mass，and also influences the stability of surrounding rock significantly.This paper mainly analyzes the stress of surrounding rock and lining considering four factors of release ratio of initial stress，distance of joint，integrity of joint and buried depth of tunnel in construction of tunnel with UDEC code.The results show that:①the stress of lining decrease with the increasing release ratio of stress，however，once it reaches certain value，the upper covering rock mass slides and collapses，then the main bearing position turns from invert to vault; ②the increasing distance of joint enhances the integrity of rock mass，which improves the self-bearing capacity and whole stability of surrounding rock;③the inclination angle of joint influences the main bearing position of lining structure;④the yield elements，together with the internal force of lining structure，significantly increase with the increase of buried depth.

Key words: Tunnel, Joint rock, Discrete element method, Numerical simulation, Stability