On the basis of system safety engineering theory and fire theory,combining the characteristic of the uncertainty and subjectivity of tunnel fire and its traditional fire risk analysis method,a model of tunnel fire named Fuzzy Fault Tree Analysis(FFTA)was built．Using triangle fuzzy theory,the fuzzy probability of basis accidents and roof accidents based on experts scognition degree was achieved,then the fuzzy grade of each factors’ relevance giving rise to gas explosion was obtained also．The result show that fire and fuel is the main elements leading to tunnel fire,following by fire-fighting measures ineffective．In order to reducing the risk of tunnel fire,ensuring the safe operation and sustainable development of road transport, we analysis the various factors and its logical relationship of road tunnel fire comprehensive,monitor the possibility of tunnel fire dynamically,and work out the strategy of active and passive fire protection．