To meet the requirements of ultra-high speed protection on UHV transmission lines, this paper proposes a fault phase selection method based on the characteristic of wavelet analysis which can detect the mutations’ time and size of singular signal in fault signal. Firstly, this method transforms the transient fault current into model fault current to eliminate the impact of the various phases’ coupling, then extracts its singular ingredients and modulus maximum by discrete wavelet transform (DWT), treats the normalized modulus maximum as the criterion factors. Finally, it summarizes the relationship among criterion factors according to the characteristics of mode fault current, and constructs a new UHV fault phase selection method. Through PSCAD simulation and Matlab calculation, this method is proved that it is disturbed less by amplitude of the transient fault signal, and it has a good adaptive capacity and a strong ability for fault resistance, and its speed is also fast and accurate, the proposed approach can be implemented simply and effectively.