The invention discloses an electricity larceny prevention meter box alarm. The right end of a capacitor C7 is connected with a bridge rectifier circuit. The upper end of a resistor R2 and the upper end of a resistor R2' are connected with a power pin VDD. The lower end of the resistor R2 and the upper end of a resistor R3 are connected with the left end of a resistor R4. The right end of the resistor R4 and the left end of an adjustable resistor R5 are connected with the negative input end of a left quadri-operational amplifier LM324. The lower end of a coil L, the lower end of the resistor R3, a resistor R3' and the lower end of a capacitor C1 are all connected with the upper end of a bidirectional thyristor. The lower end of the resistor R9 is connected to the base of the transistor BG1.The collector electrode of a triode BG1 is connected with a bidirectional thyristor and the lower end of a resistor R10. One end of a piezoelectric ceramic is connected with a pin 10 of an alarm integrated circuit SGZ07 and the other end of the piezoelectric ceramic is grounded. The alarm is simple in structure, is simple in circuit, is small in size, can freely adjust the threshold value, is wide in application range, and is low in cost.