The ship shaft-rate(SR) electric signal, as an important kind of target characteristic, plays an important part in  signal detection. In order to improve the remote-detecting capability of ship shaft-rate electric field, a novel detection algorithm based on spatially selective noise filtration in the wavelet domain was proposed. First, the signal and noise was separated by the spatially selective noise filtration in the wavelet domain. Then the arithmetic of estimating noise energy threshold of SR electric signal was proposed. Finally, the signal energy in the feature spectrum was extracted to detect the target by the sliding power spectrum algorithm. The effectiveness of the algorithm was verified by the data measured both in the laboratory and seawater. The verified result shows that the algorithm can detect the weak shaft-rate electric signal more effectively at  lower SNR situations.