For the most commonly used method for calculating reactive power, there is a big error on the condition of continuous improvement of the harmonic content. In this paper, the reactive power metering algorithms based on Hilbert digital filter are used. The fundamental wave and its harmonic components of the voltage are phase-shifted -90°and their amplitudes are retained constant. And then the active power metering method is used to meter reactive power. Moreover, the optimal designing method and the half-band filter method are respectively used to design FIR and IIR Hilbert digital filter. And the simulation results of the corresponding amplitude and phase frequency characteristics are obtained. Finally, the result is obtained that in the grid environment containing 24 harmonic, two types of reactive power metering systems have similar measurement accuracy, and that FIR filter has a better phase balance.