In this paperwe present a low complexity user grouping algorithm for multi-user MIMO system employing opportunistic fair scheduling (OFS) and zero forcing beamforming (ZFB), and develop a framework for cross-layer resource scheduling. Given a particular subset of users and their channel conditions, the
optimal beamforming scheme can be calculated. The multi-user resource scheduling problem then refers to the selection of the optimal subset of users for transmission at each time instant to maximize the total throughput of the system. The simulation result shows that the performance of resource scheduling algorithm based on user grouping method proposed in this paper is close to the optimal performance which used exhaustion method. In addition, user grouping does not affect the fairness among all users.