Disclosed herein are an ultrasound imaging apparatus and a control method thereof. The ultrasound imaging apparatus includes: a display unit configured to display an ultrasound image and an external image such that a first reference line overlaps the ultrasound image and a second reference line overlaps the external image； an ultrasound probe configured to receive a command for moving or rotating at least one image of the ultrasound image and the external image based on a predetermined reference coordinate system； and a controller configured to determine whether the ultrasound image matches with the external image according to manipulation of the ultrasound probe, and to control the display unit to synthesize the ultrasound image with the external image and to display the ultrasound image and the external image, if determining that the ultrasound image matches with the external image.
