The invention discloses a method for removing nitrate nitrogen in water through chemical denitrification. The method comprises the steps that zinc-silver double-metal fragments and ethylene diamine tetraacetic acid are added into wastewater, the pH value of the wastewater is adjusted, stirring is performed under the condition of air isolation to enable a nitrosation reduction reaction to be generated, filtering is performed, and filtrate is collected; urea is added after the pH value of the filtrate is adjusted, and denitration is performed under the condition of air isolation. The selectivity that a final reduction product is nitrogen is improved through a galvanic couple primary battery and the urea coupling denitrification method; due to the fact that the adopted raw materials are low in cost and good in compatibility with the environment and the final product of denitrification takes nuisanceless nitrogen as the main product, the method has the advantages of being green and environmentally friendly. The method is simple in technology, convenient to operate, mild in reaction condition, low in cost and suitable for industrialized mass production.