A method for inverting and classifying a seabed surface sedimentary layer by using forward scattering intensity comprises: constructing a forward scattering mode based on bistatic sonar, the mode being a single-transmission multi-reception bistatic sonar forward scattering mode; constructing a forward scattering intensity inversion sedimentary layer geological model, including: denoting the scattering intensity of a target seabed area according to a Jackson scattering model, and creating a seabed forward scattering intensity model based on a small slope approximation theory; and classifying the geological conditions. The method can observe the forward scattering. Compared with a monostatic geological inversion, the bistatic geological inversion scattering model can obtain more scattering characteristic information of the target seabed area, is favorable for verifying the results of classification of the substrate using back scattering. The bistatic sonar has a large detection range, good crypticity, and good flexibility.