There are provided embodiments for estimating the motion of at least one particle by using vector Doppler. In one embodiment, by way of non-limiting example, an ultrasound system comprises: a processing unit configured to form vector information of a target object based on ultrasound data corresponding to the target object, form a plurality of Doppler mode images based on the vector information, set at least one particle on the Doppler mode images based on input information of a user, and estimate a motion of the at least one particle based on the vector information.
