Abstract: In order to guarantee multicast quality of service(QoS),a beamforming optimization model for multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) is proposed.In the model, signal to interference plus noise ratio(SINR) of all members in a multicast group is above the threshold.Then the maximum MIMO diversity strategy and the corresponding optimized receiving beamforming algorithm are suggested.Finally, the solutions of transmitting and receiving beamforming vectors are obtained by software define radio(SDR) algorithm,and the minimal transmitting power can be obtained while the SINR for QoS is guaranteed.The simulation results and the performance analysis show that in the multicast beamforming optimization manner for guaranteed SINR,not only the minimum transmitting power can be obtained,but also the fairness performance among members in a multicast group is improved,and some other important conclusions are deduced.