The invention provides a drive circuit for a vehicle-mounted humidifier. The drive circuit comprises a voltage switching circuit and a drive circuit body. The positive pole switching-in end of the voltage switching circuit is connected with the positive pole of a power socket. The negative pole switching-in end of the voltage switching circuit is connected with the negative pole of the power socket. The positive pole output end of the voltage switching circuit is connected with the positive pole input end of the drive circuit body. The negative pole output end of the voltage switching circuit is connected with the negative pole input end of the drive circuit body. The drive circuit body comprises an inductor L1, a resistor R2, an electrolytic capacitor C1, a resistor R2, an audion Q1, a resistor R3, an inductor L2, an inductor L3, a resistor R5, an audion Q2, a capacitor C2 and a piezoelectric ceramic plate. By means of the voltage switching circuit and the drive circuit body, the piezoelectric ceramic plate can be directly connected with the power socket of an automobile, so that the purpose of humidifying air in the automobile is achieved. The circuit is reasonable in design, low in cost, convenient to use and beneficial for use; according to the circuit, the power socket on the automobile can be directly used, and a voice control melody lamp can flash.