Abstract: As the semi-active control devices are widely used in the field of civil engineering in recent decades, the simulation of the mechanical mechanism of MR dampers has made great progress. The parametric model of MR dampers has limitations in modeling, and the accuracy and efficiency cannot be achieved simultaneously. Non-parametric models based on nonlinear parameter identification and artificial intelligence methods always lack physical meaning and the accuracy depends on the training data. Based on the current situation, a hyperbolic tangent model considering response delay is proposed in this paper. In order to make the model take into account the influence of input characteristics, the sensitivity coefficients of model parameters are calculated, and GA-least-squares optimization method is used to identify parameters with higher sensitivity, the accuracy of the numerical model is greatly improved. The root-mean-square error (MSE) with the test results is used to evaluate the optimization effect.