Abstract: For combined lining tunnel,initial liner is the most dangerous when temporary supports are dismantled before construction of second-layer liner.Calculation model for dismantling temporary supports based on force equilibrium is developed and the variations of the internal forces in initial liners of large span tunnel during temporary supports dismantling is studied with increment method.A tunnel excavated with Glasses Method in Gu-Xuan section of Nanjing subway is used as an example.The influences of dismantling sequence on the internal forces of large span tunnel with different cross section sizes are analyzed and reasonable dismantling scheme is proposed.The one-time dismantled length is also obtained with 3D calculation.