Eu（NTO）₃·（H₂O）₅]·5H₂O was prepared by mixing the aqueous solution of lithium 3-nitro-1,2,4-triazol-5-onate and the dilute nitric acid solution of europium oxide.The sigle crystal structure has been determined by a four-circle X-ray diffractometer.The crystal is monoclinic,space group P₂1/n with crystal parameters of a=18.702（2）,b=6.548（3）,c=19.323（3）Å,β=95.33（1）°,V=2358.3（5）ų,Z=4,Dc = 2.026g/cm³,μ=27.678cm^-1,F（000）=1432.The final R is 0.0233.