Disclosed are a pedestrian detection method of a vehicle and a pedestrian detection system thereof. The pedestrian detection method includes transmitting and receiving a radar signal to and from an object in front of a vehicle to sense the object; capturing an exterior image of the vehicle; calculating a distance between the vehicle and the sensed object, detecting the sensed object in the captured image, and setting a region of interest (ROI) including the sensed object; and detecting a pedestrian in the ROI.