An indirect measurement method is adopted to identify the bridge's natural vibration characteristics by vibration response of vehicles crossing the bridge, it can avoid the disadvantages of the traditional method of measuring bridge frequency in dynamic load test, such as complicated operation and high cost, Based on the theory of vehicle-bridge coupling vibration and the basic principle of bridge indirect measurement method, the finite element model of vehicle-bridge coupling vibration is established for a skew beam bridge in practical engineering, A biaxial half-car model is used to measure the vehicle and extract the time-history response of the vehicle acceleration when the vehicle passes the bridge at a constant speed, Excluding known vehicle-related frequencies, The first three natural frequencies of the bridge are identified, The influence of six different vehicle speeds, six different vehicle weights and eight different bridge skew angles on the bridge frequency identification is analyzed. The results show that, The indirect measurement method can effectively identify the frequency of Bridges with high density, When the speed is less than 20km/h, the third-order frequency of skew beam bridge can be well recognized, When the speed is high, the frequency information of the bridge cannot be recognized; The relatively small ratio of vehicle and bridge mass to bridge frequency identification is advantageous; The accuracy of frequency identification is not affected by the different Angle of oblique beam bridge ;When the bridge deck is rough, the method of acceleration subtraction can still be used for frequency identification. Numerical simulation shows that the indirect measurement method still has a good recognition effect for the irregular skew beam bridge frequency. To promote the application of motion sensing indirect measurement method in bridge inspection engineering.