Free-space optical communication is a focus in recent research. Because of the influence of weather conditions, the transmission channel of free-space optical communication dramatically changes. This paper describes the design of a new adaptive rate-controlled optical communication system. The rate adaptively changes through the estimation of the received signal strength. Usually estimate the channel conditions with a low rate of radio frequency feedback. Previously the author used a new technique to design an adaptive rate-controlled optical communication system. It used beacon calibration instead of radio frequency feedback. In this paper an outdoor experiment is performed along a 186 meters horizontal path. On-off Keying modulation is used. The preliminary results with adaptive rate control are compared with that of without adaptive rate control. It appears to be at least an order of magnitude decrease of the bit-error rate.