A belt type electrostatic separator was constructed to grade seeds and remove impurities.The seeds are charged by the drum charger and the ionizing electrode stuck to the conveyer belt separates the grains via electrical attraction and based on their density.Different seeds such as wheat,barley,and mustard were used in the experiment.The results of the present study showed that using the electrostatic separator had significant effects (P<0.05) on the purity and 1000-seed weight of all used seeds.Suitable voltages and moisture contents (w.b.) were found viz.11.5 kV and 6.7％ for wheat,11.5kV and 6.3% for barley,and 10 kV and 3.5% for mustard.With increase of dielectric constant of the seeds,voltage has to be increased accordingly.Higher moisture content leads to no separation.The germination test showed that the electric field of this separator had no significant effects on improving the germination of wheat and mustard but caused significant differences in germination percentages of was found in case of separated barley seeds when compare control.The improvement gained in barley germination was 17.34% higher than that of the control.