An ultrasound system includes an ultrasound probe, N switch elements and a processing unit, wherein the N switch elements are electrically connected to the ultrasound probe, the processing unit is electrically connected to the ultrasound probe and the N switch elements, and N is a positive integer. The ultrasound probe transmits and receives an ultrasound signal by a scanning frequency. Each of the switch elements has a main output frequency. The processing unit converts the ultrasound signal into an ultrasound image. The processing unit determines whether a noise exists in the ultrasound image. When the processing unit determines that the noise exists in the ultrasound image, the processing unit adjusts the main output frequency of at least one of the N switch elements.
