The present invention provides a wheelbase adjusting device of vehicle performance test equipment, pertaining to technical field of vehicle performance test. The device comprises a wheelbase rod, fixing blocks and a threaded rod. Each fixing block is arranged on one side of the wheelbase rod separately, the threaded rod is located at the middle end of the wheelbase rod, each side of the lower endof the wheelbase rod is fixedly connected with a fixing rubber plate separately, the lower end of each fixing rubber plate is fixedly connected with a supporting base separately, and one side of eachsupporting base is provided with a sealing sleeve separately. The structure of the wheelbase adjusting device of the vehicle performance test equipment is stable, and when a supporting block is connected with a depressing slot, the supporting block is subjected to a certain resistance with the help of the depressing radian on one side of the depressing slot. When the supporting block is subjectedto a certain resistance, the device can keep a shock damping rod and a fixing rod to be fixed integrally to avoid position deviation of the shock damping rod and the fixing rod, so that when a vehicleis on the wheelbase rod and vibrates pressingly under the influence of self weight pressure of the vehicle, the stability of the wheelbase adjusting device can be well protected.