The key of maintaining the tunnel stability lies on how to deal with the advance core soil ahead of working face, which is obtained on basis of analysis on the problems in high speed railway tunnels with big crosssections in soft surrounding rock or soil. Fullface prereinforcing method by fiberglass bolts can enhance the equivalent rigidity of the advance core soil and control the deformation of the advance core soil, so that arch effect can play its role naturally and assure the excavation safety. The paper presents some basic concepts for the fullface prereinforcing method by fiberglass bolts and takes the finite element method to implement 3D numerical simulation of this construction method. Simultaneously, the basic application principle of this method in design and construction is presented. This paper can provide theoretical support for the application and popularization of this method in tunnel construction.