In order to analyse bridge structure system reliability, studied various uncertainty factors on the influence of the bridge reliability, using the stochastic finite element method to analyse bridge reliability, according to the influence of bridge structure reliability uncertainty factors, including geometric parameter uncertainty, material properties uncertainty, the bridge weights uncertainty and the vehicle load uncertainty.According to the bridge actual working condition, respectively used stress and deflection deformation as the bridge structure safety control index, established 2 each reliability function, that is, considered the structure of the two failure mode.Using Monte-Carlo method to analyze the bridge structure reliability, verify the reliability analysis method is feasible, the bridge reliability about sensitivity factors, and provides the basis for the bridge structure reliability analysis.