In order to make full use of the Doppler shift information in the phase-modulated signal, we combine the frequency-discriminating parameters in the direct current with beat components of the phase-modulated signal in sequence to construct a new frequency-discriminating parameter. It is proved theoretically and experimentally that the new frequency-discriminating parameter inherits the characteristics and advantages of amplitude-Doppler shift measurement of phase-modulated beating frequency signal. In comparison, the dynamic range is increased by about one times and the measuring accuracy is improved approximately by six times. In order to make use of the idle optical power of the echo signal, we propose a new dual-edge phase Doppler shift measurement method based on the new frequency-discriminating parameter. It is proved theoretically that the proposed method can double the measurement sensitivity.