From the generalized constitutive law of geo-material elastic-plastic model, the problem of model identification among one model type is transformed to a problem of parameter identification. So, using the new bionics algorithm-Immune Evolutionary Programming (IEP) proposed by author recently, the elastic-plastic model identification among one model type is studied, and a new model identification method is proposed. At last, this method is verified by a numerical example. The results show that, this method can get the su...