The invention provides an ultrasonic scalpel center frequency dynamic adjustment method and an ultrasonic scalpel. The method comprises the following steps: S1, starting up and presetting bandwidth and center frequency according to attributes of an ultrasonic scalpel handle vibration system, and calculating a sweep frequency range; S2, conducting frequency sweeping to obtain initial resonant frequency of the ultrasonic scalpel handle vibration system; S3, setting the initial resonant frequency as a new center frequency to obtain a new resonant frequency range; S4, starting to work from the newcenter frequency, and carrying out resonance frequency tracking. According to the method, the optimal resonant frequency of an accessed knife bar is allowed to be inconsistent, the optimal frequencyswept by the ultrasonic scalpel can be used as the working frequency, knife bars of different types can be replaced in the using process, and each type of knife bars is allowed to play a better role.In addition, adaptability of the ultrasonic scalpel is enhanced, and the problem that frequency sweeping operation is complex and frequency sweeping design is unreasonable (the knife bars are bent orbroken) is solved.