Abstract: Seismic vulnerability models of skew highway girder bridges were developed using the incremental dynamic analysis approach, and simplified calculation methods of vulnerability were discussed. According to the different pier types, supporting types and design of old and present specifications, the skew highway girder bridges were categorized into eight groups. The samples of 240 benchmark bridges were constructed with different values of the bridge structural parameters, which were determined and summarized by using the random sampling method. On the basis of the benchmark samples, a series of new bridge samples were created with varying values of the skew angles. By using the incremental dynamic analysis method, the seismic vulnerability of the bridge samples with the same skew angles was analyzed. The relationship between the skew angles and the seismic fragility parameters was analyzed. The results showed that the median value of the seismic fragility decreases when the skew angle is increased while the logarithmic standard deviation of the seismic fragility changes in the opposite trend. A new correction formula of the median value was fitted and proposed for the existing skew highway bridges in China. Values of logarithmic standard deviation were also recommended. A simplified calculation method for seismic vulnerability of skew highway bridges was derived. The relevant result could be beneficial to the seismic risk assessment and the retrofitting codes of skew bridges.