Abstract: The influence of structure-soil interaction (SSI) on identification of damage to structure was studied using time domain and least-square methods. The parameters of a structure such as rigidity can be identified by forcing the structure into vibrating and observing its dynamic response, thus identifying the damage to the structure. During the computation of structure response and model identification, no matter SSI is considered, the identified parameters converge at the true value with lowering sensor noise. When SSI is taken into account in the computation of structure response but not taken in model identification, no matter the restriction on feasible domain is considered, the identified parameters converge at the true value with no relation to sensor noise and, as result of identification, and the dependability is very low. So the influence of SSI can not be ignored.