Based on the rotational spring model, the characteristic equation of the cracked simple surpported beam is derived, the ＂point of intersection curves of the characteristic equation method＂ is proposed and combined with the ＂added mass＂ method, the method involves obtaining plots of its depth with the crack location for the first three natural frequencies through the characteristic equation. The point of intersection of three curves gives the crack parameters, the misjudgement problem of the damage location due to the symmetry is solved. The results of the simulation demonstrated the accuracy of the method.