Magnetorheological elastomer (MRE) base isolator is a new semi-active control device that has recently acquired more attention. This paper proposes a new model for MRE base isolator to portray the nonlinear hysteresis between generated force and the displacement. In this model, a hyperbolic expression is proposed to compare with the classical Bouc-Wen model, which includes internal dynamics represented by a nonlinear differential equation. For the identification of model parameters, a modified artificial fish swarm algorithm is adopted using the experimental forcedisplacement/ velocity data under different testing conditions. In this algorithm, a self-adaptive method for adjusting the algorithm parameters is introduced to improve the result accuracy. Besides, the behaviours in the algorithm are simplified to descend the algorithmic complexity. Parameter identification results are included to demonstrate the accuracy of the model and the effectiveness of the identification algorithm.