Fertilizer contains not only one compound or one element,so it is important to determine the contents of other elements necessitous and beneficial to plant.All the other nutrient elements for plant,including necessitous elements and beneficial elements in ammonia nitrogen fertilizer ((NH₄)₂SO₄) and CO(NH₂)₂,were analyzed by method of ICP-MS.The results showed that ammonia nitrogen fertilizer ((NH₄)₂SO₄) and CO(NH₂)₂ both contain many necessitous elements,Mg,P,K,Ca,Mn,Fe,Ni,Cu,Zn and Mo,thereinto the contents of Mg,P,K,Ca,Mn and Fe were on μg·g-1 the level,and Ni,Cu,Zn and Mo were on the ng·g-1 level;compared with CO(NH₂)₂,ammonia nitrogen fertilizer ((NH₄)₂SO₄) contains more necessitous elements and beneficial elements except Mo and Si.All the above elements could influence the results of nitrogen fertilizer efficiency experiments,so pure fertilizer should be used in the future nitrogen fertilizer efficiency experiments and the comparative experiments of different form nitrogen fertilizer.