Abstract: Nitrate would turm into nitrite by enzyme and microbial action Within human body.Under certain conditions nitrite would react with protein and turn into nitrosamine,which was provedtobe the most suong carcinogen by the animal tests .while the state standard assay method of findins the nitrate content in vegetables has been only the cadmium calumniation method,but its operation would takea long time,and its test process was complex,so it could not meet the vegetable fast circulation requirement.Hence the Nitrate Radical Ion Selectivity Electrode Method would not only simplify the operation process but also shorten the fest time,so it could be an ideal method.

Key words: Nitrate radical ion selectivity electrade Selectivity coefficient Electrode force