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The acid pre-washing of zero valent iron for improvement the removal effi-ciency would deduce the secondary pollution in groundwater,as well as more fine particles of zero valent iron would reduce the permeability of aquifers.In order for better understanding of the approaches of nitrate removal,a series of laboratory experiments were conducted in this study.Batch tests showed that washed zero valent iron powder and activated carbon are more efficient to remove nitrate than cemarite and zeolite,similar with the acid pre-washing zero valent iron.X-ray diffraction phase analysis showed that a kind of oxide Fe3O4 generated on the surface of the washed iron powder particles,which is mixed with Fe2O3 and FeO,is relatively loose,can improve the efficiency of nitrate removal.Continuous flow column sys-tem test showed that the coarse sand-zero valent iron mix(R1),the coarse sand-zero valent iron-activated carbon mix(R4),and the coarse sand-zero valent iron-sawdust mix(R5)are more effective to reduce nitrate than the coarse sand-activated carbon mix(R2)and the coarse sand-sawdust mix(R3).Components such as NO2-N、NH4+-N would have environmental concerns as well.Further chemical analysis on the fluids from nitrate removal treatment indi-cate that R1 and R4 to be the most effective and also environmentally friendly media for ni-trate removal.This study showed that R1 and R4 media could be developed into a viable technology for the removal of nitrate in high concentration of polluted groundwater.