The beam with orbital angular momentum is a present domestic and foreign research key direction.Its application and development will bring the profound influence in the optical communication field. The research progress of the beam with orbital angular momentum and encoding information as light's OAM for free-space optical communication were reviewed and the existing design method,w rking principle,effecting factors,mechanism and description methods of encoding information as light's OAM were discussed. Based on these analysis,the prospect of future development in the encoding information as light's OAM for freespace optical communication were also forecasted.