Abstract: The static RCS data is usually used for establishing fluctuating targets’ echo model in engineering, the accuracy and rationality of it urgently need verification. A simulation method for dynamic RCS data was proposed in this paper according to aerodynamic theory and the dynamic data of F-117A stealthy attacker’s spiral flying was acquired. Two kinds of data were compared on statistical parameters, correlation characteristics and fluctuating model. The differences between dynamic and static RCS characteristics on evaluation of fluctuating targets’ detection ability were analyzed. The results show that it’s hard for static data to reflect true radar characteristics when target is moving, using static data to describe target characteristics may lead false conclusion.