When the viaduct or its components are damaged and fail to function normally, the bridge is considered to be invalid. Taking a six-span continuous beam viaduct as the engineering background, a three-dimensional nonlinear finite element calculation model was established by OpenSees software. Based on IDA analysis method and weighted rank sum ratio method, the continuous collapse failure mode of the viaduct under strong earthquakes is identified. The friction slip of bearing is considered in the calculation process, the state of the component is judged according to the change of the damage value, the failure sequence of each component of the continuous beam bridge is counted, and statistically significant failure modes and weakest failure modes are given. The results show that the failure mode based on the weighted rank sum ratio method is basically the same as the weakest failure mode. First is the failure of the sliding support that acts as friction damping, followed by the failure of the fixed pier and the fixed bearing, and finally is the failure of the non-fixed pier. The research methods and conclusions in this paper can provide some reference for the seismic analysis and earthquake failure collapse simulation of similar continuous beam viaducts.