Abstract: There are often cavity between lining and surrounding rock because of some reasons, such as construct conditions and technologies etc. During constructing tunnel, and then result in the lining endure asymmetric load on it,at the same time the position of cavity can not offered resistance to constrain displacement of lining and produce disease which lead to the lining maintained. The paper taking the building tunnel of BI Jia mountain as prototype in chongqing city and geometric similarity ratio of 1∶25 adopted in model test. Applying the same load on the structure till it produce the disease, and then apply load again while the structure was destroyed after taking different reinforcing mode in same rock mass and the same defect. Through contrasting backfilling pressure casting with other reinforcing mode and conclude the backfilling pressure casting should be the first selection while cavity existed.