Single parameter alarm system have the defects of high false positives, frequent alarm and weak abilities to comprehensively analysis the parameters because abnormalities usually occur in the water quality monitoring. As a result, this paper designs an alarm system to monitor the process that can intelligently analysis parameters combined with the duration of the alarm by using fuzzy reasoning method. Besides, the alarm output is divided into several levels, and corresponding services will be triggered by the alarm output in different levels. At the same time, the operators can get the detailed information of the alarm in the shortest time and take the valid control strategies. Finally, the system will achieve the optimal control with safety.