The invention discloses a method for obtaining a sub-information channel modulation code, comprising the following steps: sending a request message requiring for providing sub-information modulation code information to an opposite terminal station, wherein the request message contains a control field in a preset format, and the control field comprises a sub-information channel modulation code information request, a training request, an MCS request or an antenna selection indication, an MCS feedback and an antenna selection order/data; and receiving a response message from the opposite terminal station, wherein the response message comprises a data frame structure packaged with sub-information channel modulation code information in the preset format, the sub-information channel modulation code information data frame is carried with spatial stream information, sub-information channel modulation mode and encoding speed of each spatial stream, and subcarrier grouping information. In the invention, frame structure and frame interactive sequence are designed reasonably, and adaptive modulation encoding on each sub-information channel which is composed of subcarrier groupings is supported, thereby effectively overcoming frequency selectivity of a system, improving system performance, and securing backward compatibility with current system to the greatest extent.