Abstract: In order to evaluate the applicability of Monin-Obukhov similarity theory and the eddy covariance system in high-standard farmland, this paper analyzed the atmospheric characteristics, including atmospheric stability, turbulent variance similarity, power spectra and cospectrum, turbulent intensity and turbulence kinetic energy, using the observation data of the eddy covariance system over the underlying surface of a high-standard farmland in Nantong, Jiangsu Province. The results show that the atmosphere over the farmland is unstable during the daytime and stable at night. The variation of normalized standard deviation of three-dimensional wind components with atmospheric stability obeys the “1/3” power law. The normalized standard deviation of temperature, specific humidity and CO₂ density with atmospheric stability follows the “1/3” power law when atmosphere is unstable. Therefore, Monin-Obukhov similarity theory is applicable at such a high-standard farmland. In the inertia subregion, the power spectra of three-dimensional wind speeds follows the “-2/3” slope relation, and the cospectrum of vertical wind speed and scalar quantities follows the “-4/3” slope relation. So, the sensible heat, latent heat and CO₂ fluxes over the high-standard farmland can be correctly observed by the eddy covariance system. The three-dimensional turbulence intensities decrease with the increase of wind speed, showing horizontal results stronger than those in vertical direction. The turbulent kinetic energy (TKE) increases with the increase of wind speed, following a quadratic function. TKE is high during the daytime and low at night, reaching its maximum under neutral atmosphere. Compared to thermal turbulence, mechanical turbulence contributes more to TKE. The research can advance our understanding of the energy and mass exchanges between high-standard farmland and atmosphere in East China.