Spectrum of shortwave channels becomes less and less, audio interference has such relatively high density that SNR of received signal worsen badly in the wideband shortwave probe system. The traditional SVD filter loses the power of probe signal in the frequencies of interference, which results in disadvantageous influence to the high accuracy estimation of channel parameters. This paper analyses the internal mechanism of SVD filter, derives the analytical expression of SVD filter and estimates the useful power from signal plus noise subspace ,then presents a novel SVD filtering algorithm based equalization of power. The simulation and data processing of our probe system both demonstrate that the new algorithm not only realizes audio interference rejection, but also effectively reduces power loss of probe signal. Therefore, this algorithm has special important meaning to the high accuracy estimation of the shortwave ionosphere parameter.