Disclosed are a three dimensional (3D) ultrasound system and a method of operation of the 3D ultrasound system providing a reflection angle of an ultrasonic wave beam. As an example, the ultrasound system may include a probe to sense an ultrasonic wave beam radiated to an object and reflected from the object, and to form a scan region with respect to the object, a reflection angle calculation unit to calculate a reflection angle formed by a reflection of the ultrasonic wave beam at each spot in the scan region, and to store the calculated reflection angle in a table, and a reflection angle display unit to display, based on the table, the reflection angle at a first spot where a point is designated, by interpolating using a point designation order with respect to the scan region.
