The ion selection electrode method is used to measure the ammonia nitrogen concentration. The ammonia nitrogen ion selection electrode directly detects the ammonium root ions in the water environment to determine the concentration of ammonia nitrogen. The pH electrode is used as the reference electrode to obtain better stability. The ammonia nitrogen sensor consists of ammonium ion selection electrode, pH electrode and temperature electrode to form an integrated sensor, which can correct and compensate for the measured value of ammonia nitrogen with each other, and realize multi-parameter measurement at the same time.