This paper describes the design and implementation of a cotton flow sensor for use in cotton gin. The sensor is utilizing electro-optic technology. The sensor combines emitters and detectors mounted on the lint conveyers. As the cotton passes through the conveyer it is illuminated by infra red light of the emitters. The detectors which are positioned across the conveyer detect light pulses. The pulse count is proportional to the volume and density of the cotton. The pulse count can then be used to estimate the mass and the rate of the cotton passing through. The rate information can be processed in real time to produce a sensing and controlling signal s(or data and command strings) for the gin machinery. This technique enables operators of the gin improve on the efficiency and throughput of the facility.