Abstract: With high intensity focused ultrasound being widely applied clinically,much attention has been laid on monitoring temperature in target areas.We study methods of measuring temperature during HIFU by taking sound propagation speed and attenuation in the tissue.This method is very convenient therefore is useful in medical treatments.We provide curves describing the change of propagation speed and attenuation with respect to the temperature in porcine liver.It has been shown that,when the temperature reaches 70~75℃,the slope changes sharply.Since the temperature at which protein denaturalizes is 63℃,we can control and monitor the HIFU therapy when the temperature reaches the critical point.