Directional antenna technique is adopted to enhance the outage performance of cooperative communication. Protocols which are suitable to bidirectional single relay AF cooperative communication based on directional antenna is proposed on the basis of the traditional Protocols and the outage probability low bound of TR-BF TDBC and OSS systems are derived theoretically. Simulation results show that the derived low bound and the exact value are very tight when SNR is high or the channel coefficients from two ends to relay vary widely. The outage performance of OSS is better than that of TDBC，and the outage performance of TR-BF AF cooperative communication is better than that of the traditional one when spectral efficiency is not very high. Usually, the outage performance of cooperative communication system with full directional mode is improved, and OSS protocol should be adopted as far as possible in practical applications in order to fully gain best of its advantages.