The invention discloses a DC electric energy metering device and method based on spectrum analysis and synchronous sampling. The device comprises a DC voltage sampling module, a DC current sampling module, a frequency phase synchronization module, a frequency analysis module, a DC electric energy calculating module and a ripple electric energy calculating module, wherein the DC voltage sampling module is used for sampling DC voltage; the DC current sampling module is used for sampling DC current; the frequency phase synchronization module is used for enabling the sampling frequency and the phase of DC voltage sampling and DC current sampling to be the same; the frequency analysis module is used for using Fourier transform to process sampling signals; the DC electric energy calculating module is used for calculating DC electric energy; and the ripple electric energy calculating module is used for calculating ripple electric energy. In the method, phase and frequency synchronization for DC current sampling and DC voltage sampling is adjusted, the DC current and the DC voltage are sampled, and the DC electric energy is obtained after Fourier transform is carried out on the DC current sampling value and the DC voltage sampling value.