Abstract: A micro bar code and a recognition system and method thereof are provided. The micro bar code has a plurality of nanomolecules disposed thereon in a predetermined arrangement. In the recognition system and method, a sensing module senses the arrangement of the nanomolecules on the micro bar code. The sensing result from the sensing module is transmitted to an operating module and then inputted to a bar code database that stores information corresponding to arrangement of each set of nanomolecules, so as to recognize information on the micro bar code to be recognized. Finally, the recognition result is transmitted back to the operating module for recording. The micro bar code has advantages of small size and large data storage capacity.