Schumann Resonance relates with global temperature variations, new geophysics phenomena in the low ionosphere and short-term earthquake prediction etc. In this paper based on the nonlinear modulation model of high frequency and extreme-low frequency electromagnetic waves in low ionosphere, the Schumann Resonance observing is researched. Taking the fair weather electric field in account, the cross modulation index was 4.2×10-4. At the first Schumann Resonance observatory of China, the first 4 peaks of Schumann Resonance respectively at 7, 14, 20, 26Hz were obtained in demodulation spectra of the high frequency time service signals. The parameter characteristics of Schumann Resonance in the low ionosphere were analyzed under the geographical condition of middle latitude area. The feasibility of Schumann Resonance measurement by demodulating the spectra of HF has been verified. The non-linearity between Schumann Resonance and very low frequency signals also was discussed.