A multi-bit optical computing system includes an optical source module for generating multi-frequency optical signals. An optical information storage module receives each of the multi-frequency optical signals through an optical path module, and stores them as a plurality of optical information. An optical processing module receives each of the optical information in the optical information storage module via the optical path module according to an external command, generates a plurality of output information, and stores the output information through the optical path module to the optical information storage module.