Tunnel Leakage has been a key issue of the Tunnel Engineering construction and maintenance because of the universality and serious harmfulness. Aiming at the status of tunnel Leakage in our country, this paper identifies the main factor from all kinds of factors. An evaluation indexes system is advanced which consists of 10 factors coming from following four grade indexes, including construction factors, Drainage and Waterproof Methods for Waterproof Tunnel, the situation of Surrounding Rock and groundwater and physical geography. In addition, an evaluation model based on the BP artificial network is designed. Combining with evaluation example, the calculation method is realized by software. The results show that the evaluation method is useful. The method provides a new way to increase the precision of tunnel leakage disease level evaluation.