Using the electrostatic polarization model and Hertzian contact theory, the tensile and compressive behaviors of dilute electrorheological fluids bet vr een two parallel electrodes are presented. It is shown that the load increases nonlinearly with decreasing distance of the two electrodes and is a linear function of the elastic modulus of dielectric particles. This qualitatively explains the rheopectic effect of electrorheological fluids under compressive loading.