The invention discloses a control method and system for an ultrasonic circuit of an electronic cigarette. The control method comprises the following steps: detecting a temperature T1 when the ultrasonic circuit works; comparing a set temperature T with the detected temperature T1, and controlling the ultrasonic circuit to continuously work if T1 is smaller than T-delta t; controlling the ultrasonic circuit to stop working if T1 is greater than or equal to T+delta t, wherein delta t is deviation. The control method disclosed by the invention is simple, can precisely control start-stop of the ultrasonic circuit as well as start-stop of a heating device, so that the atomizing efficiency is improved, the smoking mouthfeel is improved, the ultrasonic circuit is protected very well, the ultrasonic circuit is prevented from being damaged by cavity resonance, and the control precision is high.