Abstract: Electric charges existing on the clay particle surfaces? induce a micro-electric field, and lead to the formation of adsorbed water on surrounding clay particles. And the micro-electric field exerts an influence on the movement pattern of ion in pore water, resulting in the ion effect of seepage in clay. The two actors above will obviously change the characteristics of seepage in micropore of clays. The change of seepage property caused by the factors mentioned above is defined as micro-electric field effect on seepage (MEFES) in clay. The electric potential on the surface of micro particles? clay amounts to a few tens or hundreds of mV, and then the electric field on the particle surface greatly affect the rule of seepage. Using laboratory experiment method, MEFES in micro particle clays is discussed in this paper. A series of seepage consolidation tests are conducted for the samples of micro particle clays with different ion concentrations in pore water or particle surface electric potentials. The test results show that an increase in particle surface electric potential or a decrease in ionconcentration will result in the decrease of equivalent permeability coefficient, consolidation rate and consolidation displacement, revealing the existence of MEFES in micro particle clays.