The invention relates to a method for driving an ultrasonic transducer. The method includes the following steps: initiating a system; judging whether an upper computer instruction is received or not, and if yes, executing the next step; decoding the upper computer instruction, and executing a corresponding processing program; judging whether a welding line mark position is a first set value or not, and if yes, executing the next step; if not, resetting ultrasonic output and returning; outputting an ultrasonic driving signal; judging whether power of the ultrasonic driving signal is larger than zero or not, and if yes, executing the next step; if not, returning; tracking resonance point frequency of the ultrasonic transducer, and adjusting voltage value of the ultrasonic driving signal according to resonance frequency point impedance value. The invention further relates to a device for realizing the method. The method and the device have the advantages of high tracking speed and high conversion efficiency.