Abstract: For multipath fading channels, the modulation of common single-carrier signals are classified through the use of the order Cyclic Cumulants. The analysis and derived of fist order, second-and fourth-order cycles statistical features of a variety of single-carrier signal in multipath fading channels, and looking for characteristic difference in the statistical characteristics of the particular cycle peaks distinction ,last complete signal modulation classification using CAFR detection algorithm through the tree judgment. Verify the feasibility of the algorithm in multipath fading channel modulation classification by theoretical analysis and simulation analysis. The algorithm does not require a priori knowledge of the signal, has the robust performance in multipath fading channel and a wider application of occasions.