The invention discloses a production fault automatic alarm method and system, and the method comprises the following steps: S1, enabling a control unit to transmit a control signal to an execution unit, so as to enable the execution unit to perform an operation; S2, enabling the execution unit to return the execution reflection signal value to the control unit; S3, executing step S1 if the execution signal value is compared with the control signal value and a calculated first difference absolute value is not greater than an allowed absolute value, or else executing step S4; S4, enabling the control unit to read a measurement signal value of a sensing unit; S5, giving a drive alarm if the measurement signal value is compared with the execution signal value and a calculated second differenceabsolute value is not greater than a set execution absolute value, or else giving an execution alarm. The sensing unit is used for detecting an external signal, thereby preventing the control unit from making a wrong judgment on a fault, and improving the fault judgment accuracy.