The invention relates to a 3,5-di(2-pyridyl)-4-(4-pyridyl)-1,2,4-triazolyl-silver (I) coordination polymer, and a preparation and application thereof. The compound is synthesized by the following steps: under normal temperature and pressure, mixing AgNO2 acetonitrile solution and ligand L chloroform solution, and keeping stirring for half an hour, and standing in a dark place to volatilize for about one week, thereby obtaining the colorless lumpy monocrystal product. The invention has the advantages of simple preparation technique, short reaction time, easy after-treatment and high yield. The experiment proves that nitrite ions in the material can selectively react with tetrafluoroborate ions, hexafluorosilicate ions, nitrate ions and perchlorate in an anion exchange mode, and benzoate ions and acetate ions can not perform similar anion exchange reaction. The material overcomes the limitation to the existing anion exchange material, the exchange process is simple and easy to implement, and thus, the invention is hopeful to practical application in the field of ion exchange materials.