This paper deduces a simple formula for computing the incidence radiant flux density. Based on the definition of albedo, the authors put forward a new method of surface albedo inverse model. The TM data of the Poyang Lake were used to make a test, and the average relative error was only 4.91%. The method is easy to utilize, and it only needs spectral data of two different kinds of land covers. In addition, it doesn’t need the albedo computation of narrow wavebands. The method proves to be a good means for inversion of surface albedo.