There are provided embodiments for providing a particle flow image for representing flow of at least one region of interest (more particularly, 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 Doppler mode image based on the vector information, and set at least one region of interest on the Doppler mode image based on input information of a user, the processing unit being further configured to form a flow image for representing flow of the at least one region of interest based on the vector information.
