Nuclear power plants (NPP) contain plenty of valve piping systems (VPS's) which are categorized into high anti-seismic grades. Tasks such as seismic qualification, health monitoring and damage diagnosis of VPS's in its design and operation processes all depend on finite element method. However, in engineering practice, there is always deviations between the theoretical and the measured responses due to the inaccurate value of the structural parameters in the model. The structure parameters identification of VPS within NPP is still an unexplored domain to a large extent. In this paper, the initial 2D-finite element model (FEM) for VPS with a DN80 gate valve was updated by utilizing seismic response. The objective function used in the model updating procedure is the vibration control equation error of the VPS. The experimental results show that the updated 2D-FEM can accurately predict the original dynamic characteristic of the VPS. It was also found the Rayleigh damping coefficients corresponding to the VPS vary slightly with the change in seismic excitation amplitude. The research displayed the complete procedure of updating the complex structured initial FEM by utilizing seismic response, and the results show that the parameters can be accurately identified even if the seismic response used for updating merely contained the fundamental frequency information of the structure. © 2020 Tech Science Press. All rights reserved.