Abstract: Damping plays an important role in structural dynamics. However,it is difficult to model the damping characteristics in the finite element analysis. Using the experimental and analytical frequency response functions (FRF), a complex parameter model updating method is developed to update the mass, stiffness and damping properties. Taking the complex proportional coefficients of the element matrices as the updating variables, the direct updating sensitivity equation system is deduced, and the relationship between the complex updating parameters and the typical damping types is revealed. At the end, the performance of the proposed method is evaluated with examples of a 6-DOF lumped system and a 25 truss structure.