An ultrasound system, comprising: a user input unit configured to receive input information for setting two sample volumes on a brightness mode image; an ultrasound data acquisition unit configured to acquire first ultrasound data and second ultrasound data corresponding to a living body; and a processing unit configured to form a brightness mode image based on the first ultrasound data, set the two sample volumes on the brightness mode image based on the input information and form blood flow information corresponding to blood flow in the living body based on the second ultrasound data corresponding to the two sample volumes, wherein the processing unit is configured to form additional information based on the blood flow information, wherein the blood flow information includes blood flow velocity information, blood flow rate information and blood flow velocity distribution information, and the additional information comprises additional information corresponding to a first sample volume included in the two sample volumes and additional information corresponding to a second sample volume included in the two sample volumes, wherein the processing unit is configured to form a color map corresponding to each of the first sample volume and the second sample volume by mapping a plurality of blood flow velocities corresponding to current blood flow information as the additional information, form a color Doppler spectrum image corresponding to each of the first sample volume and the second sample volume by applying the colors corresponding to the plurality of blood flow velocities to pixels of a Doppler spectrum image as the additional information, and form a color blood flow velocity image corresponding to each of the first sample volume and the second sample volume by mapping blood flow velocities corresponding to current blood flow information as the additional information, and the color blood flow velocity image is displayed on the two sample volumes, wherein the processing unit is further configured to form a blood flow velocity distribution image for representing blood flow velocity distribution corresponding to width of Doppler spectrum as the additional information. a user input unit configured to receive input information for setting two sample volumes on a brightness mode image; an ultrasound data acquisition unit configured to acquire first ultrasound data and second ultrasound data corresponding to a living body; and a processing unit configured to form a brightness mode image based on the first ultrasound data, set the two sample volumes on the brightness mode image based on the input information and form blood flow information corresponding to blood flow in the living body based on the second ultrasound data corresponding to the two sample volumes, wherein the processing unit is configured to form additional information based on the blood flow information, wherein the blood flow information includes blood flow velocity information, blood flow rate information and blood flow velocity distribution information, and the additional information comprises additional information corresponding to a first sample volume included in the two sample volumes and additional information corresponding to a second sample volume included in the two sample volumes, wherein the processing unit is configured to form a color map corresponding to each of the first sample volume and the second sample volume by mapping a plurality of blood flow velocities corresponding to current blood flow information as the additional information, form a color Doppler spectrum image corresponding to each of the first sample volume and the second sample volume by applying the colors corresponding to the plurality of blood flow velocities to pixels of a Doppler spectrum image as the additional information, and form a color blood flow velocity image corresponding to each of the first sample volume and the second sample volume by mapping blood flow velocities corresponding to current blood flow information as the additional information, and the color blood flow velocity image is displayed on the two sample volumes, wherein the processing unit is further configured to form a blood flow velocity distribution image for representing blood flow velocity distribution corresponding to width of Doppler spectrum as the additional information.