The invention discloses a flowerpot water shortage preventing alarm circuit comprising a field effect transistor VF1, a transistor VT2 and a time-base circuit. A grid electrode G of the field effect transistor VF1 is connected to a negative power supply through a resistor R1. A drain electrode D of the field effect transistor VF1 is connected to a positive power supply through a resistor R2. A drain electrode D of the field effect transistor VF1 is connected to a base electrode of the transistor VT2 through a resistor R3. A source electrode of the field effect transistor VF1 is grounded. A collector electrode of the transistor VF2 is connected to the positive power supply. An emitter electrode of the transistor VT2 is grounded through a resistor R4. The connection structure of the time-base circuit is that a first pin of an NE555 is grounded; a second is connected to a sixth pin; a third pin is grounded via a resistor R5 and a light emitting diode LED which are sequentially grounded; a fourth pin is connected to an emitter electrode of the transistor VT2; a fifth pin is grounded via a capacitor C1; the sixth pin is grounded through a capacitor C2; a seventh pin is connected to the positive power supply via a resistor R6; a resistor R7 is connected between the sixth pin and the seventh pin; and an eighth pin is connected to the positive power supply. According to the circuit designed in the invention, the practicality is strong; people can be given timely prompt of watering so as to prevent soil drying; the structure is simple; the usage is safe; and the electricity consumption is small.