Abstract: In this paper pore pressure coefficients were studied using various constitutive models.The expressions of these coefficients for Tsinghua elasto-plastic model, modified Lade’s model and modified Cambridge model were derived. The undrained behaviors of a compacted clay with positive dilatancy and a medium sand with negative dilatancy wera predicted using above-mentioned three models, Duncan EB and linear elastic model with parameters determined from the CD test data. Some valuable conclusions have been obtained.