Constitutive modeling theory for soils is very significant in geotechnical engineering. The Cam - Clay elasto - plastic model is widely regarded as the milestone of modern soil mechanics. The concept of the model has explicit geometric and physical meanings. The Cam - Clay model and its modified model are regarded as one of several well accepted models among many proposed models. The improvement and revision based on the Cam - Clay model are the important aspect of modeling for geomaterial. In this paper, the Cam - Clay model and its modified model are introduced in brief, its limitation i
s analysed and an overview on the improvement of this model is given to farther
study. 