Abstract: Objective: The AS (advance support) before tunnel excavation is a key link in CRD (center cross diagram) method construction. The deformation and stress of surrounding rock under influence of different supporting parameters of CRD method AS small pipes are studied, to better enhance the AS effect according to the actual site conditions. Method: The underground passage connecting Dalian Henglong Plaza and Dalian Metro Line 2 People′s Square Station is taken as engineering background, and the construction site data is combined with theoretical analysis and MIDAS GTS finite element software numerical simulation test; the vault subsidence, horizontal convergence and land subsidence during underground passage excavation are taken as analysis indexes, and the external insertion angle, pipe length and circumferential distance of small pipes are studied. The support effect of various small pipe parameter combinations on surrounding rock is compared and analyzed. Optimized small pipe parameters are selected for numerical simulation. The fitting of field monitoring data and numerical simulation results show that the advance support effect is mainly related to the pipe length and external insertion angle of the small pipes, adjustment to the above factors can effectively enhance the support effect; as the effect of circumferential spacing on AS is not obvious, the circumferential spacing should be determined according to the grouting radius of small pipes. Result & Conclusion: By adjusting the parameters of the small pipes, the effectiveness of supporting surrounding rock can be evidently improved, ensuring the operation safety and construction efficiency of underground pedestrian passage.