By introducing the concept of information content, an approach of describing the effective information of different atmospheric parameters contained in atmospheric sounding data of high spectral resolution is given in the paper firstly. And then a “successive absorption” method for channel selection which uses the information content as the optimal index is designed. At last, a channel selection experiment for the retrieval of temperature is carried out. Compared with the channels used in the retrieving of AIRS products in NASA DAAC, the result of the experiment shows that the “successive absorption” method based on information content is competent for channel selection.