Use windowed interpolation algorithm for correcting the fast Fourier transform appears large computation, computing slowly, and hardware demanding situation. This paper presents a embedded platform based harmonic power monitoring terminal design. The design use of the "Center of Gravity based on M-order cosine spectral window" windowed interpolation algorithm, and 16 six-channel simultaneous sampling ADC and ARM with hardware floating point unit as the core, to complete the 50 within the harmonic energy measurement, power quality analysis, and have data display, storage, transmission and other functions. Experimental data show that the developed harmonic power monitoring terminal meets the accuracy requirements of《GB/T14549-93》Class A measuring instrument. The windowed and interpolation algorithm used simplified the hardware design, the design present in this paper has a good reference value.