A research has been proceeded at 3100 working face in Donghuai Coal Mine, for the specific geological conditions of the roadway driven along gob with the weak roof and floor. It illustrates the basic principles of roadway driven along gob by analyzing stability of the structural of overlying rock mass when the working face is tunneling and mining. The foundation to maintain surrounding rock stability at roadway driven along gob is to keep the small structure stability. By applying the method of theoretical analysis and numerical simulation, the rational narrow coal pillar width is intended to 5 m. The industrial case study indicates that the requirements in production can be met, and the working face can be mined smoothly by determining the wide of narrow coal pillar width is 5 m.