A method of generating an ultrasound image and an ultrasound system using the method, the method including: obtaining an echo signal from an ultrasound signal irradiated on an organ; calculating an amount of a change in the echo signal with respect to a reference echo signal; determining a temperature of the organ from the amount of the change in the echo signal by using an amount of a change in an attenuation coefficient of the organ that changes according to a temperature change; and generating an ultrasound image including information about the determined temperature.