The invention relates to Method for Selecting Subchannel Mode and MIMO Communication System Using the Same. A method for self-adaptively selecting a code modulation sub-channel mode is suitably used in a MIMO communication system that comprises a base station and mobile terminals, wherein the method comprises the steps of: the mobile terminal estimating channel state information thereof, and determining a sub-channel structure most suitable for data transmission thereto, based on the channel state information; the mobile terminal feeding back information on the determined sub-channel structure most suitable for data transmission thereto to the base station; and the base station determining a sub-channel structure used for a down link, based on the information on the sub-channel structure fed back by the mobile terminal. According to the present invention, the subchannel structure in the communication system can be self-adaptively changed according to the actual communication environment, so as to improve the entire communication quality and efficiency.