In order to certificate the standard substance 1,5-diazido-3-nitrazpentane(DIANP),an electrode potential titration of determining the purity of DIANP wasestablished. The conditions of the titration method were as follow: dimethysulfoxide(DMSO)as solvent, adding sodium hydroxide solution as reaction regent, andmaking N^-₃ in DIANPand Ag⁺ in AgNO₃ react to form the precipitate of AgN₃.The purity of standard substance DIANP calculated by the EQP curve was 99.85%and the relative standard derivation was 0.13%. There was no significantvaration between the results obtained by electrode potential titration and HPLCmethod. The expanded uncertainty of this method was 0.3%.