Fair-weather atmospheric electric field data observed at nine stations over mid-latitude areas of Eurasian Continent are analyzed.The results show that the diurnal variation of fair-weather atmospheric electric field exhibits in two ways:a single oscillation with a peak and trough and a double oscillation with two peaks and two troughs.The seasonal variation is obvious,which is higher in winter and lower in summer.Diurnal variation of fair-weather atmospheric electric field is negatively correlated with the air conductivity and positively correlated with both the Aitken nuclei concentration and the absolute humidity and it is also affected by temperature gradient.