A fault phase selection method is put forward according to the characteristics of transient travelling wave． The proposed method is implemented based on the difference of fault features of transient current travelling waves，whose modulus maxima of B － spline wavelet transform is obtained by the decoupled transform of non － independent three － phase fault current． The fault phase selection method fully considering the features of the four modular fault components remedies the defects of conventional fault phase selection methods． Compared with the traditional fault phase selection methods，the correctness and reliability of fault phase selection method based on the dyadic B － spline wavelet transform are improved，which is verified by the simulation of PSCAD and data analysis of Matlab．