A tracking system and a method thereof are provided in this disclosure. The tracking method includes steps of: capturing first images of the physical environment by a first electronic device; extracting a plurality of first feature points from the first images; generating a plurality of map points according to the extracted first feature points; building a map of the physical environment according to the map points by the first electronic device; capturing a second image of the physical environment by a second electronic device; extracting second feature points of the second image and transmitting the second feature points to the first electronic device; and estimating a pose of the second electronic device according to the map and the received second feature points by the first electronic device.