In this work, the eastern expressway connecting line project of Shenzhen city was studied. For the forked ‘Y’ shaped large tunnel in Guduiling mountain, the progressive failure of surrounding rock mass, the evolution laws of deformation and stress in rock mass were studied. The test results show that failure may firstly initiate at the surrounding rock mass below the waist, and then propagate upwards to the arch, so that it is necessary to embed feet-lock bolt in the rock mass below the waist to restrain the initial shear failure of rock mass. If the double side pilot method is used for the excavation of tunnel, the later excavated pilot tunnel may cause the failure of surrounding rock mass of existing tunnel, so that the middle wall between two pilot tunnels shall be reinforced accordingly. Tunnel excavation may affect the deformation of rock mass within the range of 0.95B (B for the tunnel span) above tunnel arch, but eventually the height of collapse-formed arch is only 0.5B. After the excavation of tunnel, the region with increased stress mainly locates within the range of 0.4~0.9B.