The utility model discloses a hydraulic pressure station under PLC malfunction is opened and is stopped controlling alarm system, include: the main power source, first hydraulic pressure station is opened and is stopped control button, PLC control module, an auxiliary relay, contactor and hydraulic pressure station, main power source and first hydraulic pressure station are opened and are stopped the control button electricity and be connected, first hydraulic pressure station is opened and is stopped control button and PLC control module electricity and be connected, PLC control module is connected with auxiliary relay electricity, an auxiliary relay is connected with the contactor electricity, the contactor is connected with the input electricity at hydraulic pressure station, still include auxiliary electrical power source, change over switch, second hydraulic pressure station is opened and is stopped control button and the 2nd auxiliary relay, auxiliary electrical power source is connected with the change over switch electricity, change over switch and second hydraulic pressure station are opened and are stopped the control button electricity and be connected, second hydraulic pressure station is opened and is stopped control button and the 2nd auxiliary relay electricity and be connected, the 2nd auxiliary relay is connected with the contactor electricity, an auxiliary relay is connected with the alarm electricity. The utility model has the advantages of production safety nature is high.