A MIMO communication system capable of adaptive user scheduling. The MIMO communication system comprises a transmitting terminal, which sends data frames containing at least channel estimation signal and user data, and at least one receiving terminal, which recovers the user data and generates corresponding feedback information. The feedback information comprises an optimal transmitting antenna set dedicated to the receiving terminal, the achievable channel capacity by each antenna within the antenna set, and the degradation factors caused by each of other unselected antennas to each of the selected antennas. Depending on the feedback information, the transmitting terminal generates scheduling information based on which the adaptive user scheduling is conducted. The scheduling information comprises the scheduled users, number of data streams supported by each scheduled user, and the corresponding transmitting antenna for each of the data streams. The MIMO system can achieve the optimal channel capacity through adaptive user scheduling.