Abstract:The characteristics of negative oxygen ions are compared and analyzed between typical urban and forest areas by means of the data of the 15 months hour to hour continuous measurements. The results indicate：（1） The average concentration of negative oxygen ions in typical urban areas is 240 cm-3 and 1470 cm-3 in forest areas, and the concentration in forest areas is 5 to 6 times higher than that in typical urban areas； the small ions in negative oxygen ions accounts for about 80 %, the middle ions about 20 % in forest areas， but there is few middle ions in typical urban areas. （2） The changing trend of negative oxygen ion concentration is basically identical between typical urban and forest areas; the high concentration period mainly occurs from midnight to sunset, and the low concentration period mainly from noon to evening, the peaks from 04:00 and 05:00, and the minimum at 13:00 （3） The highest negative oxygen ion concentration seasons in forest areas are spring and winter, but that in typical urban areas in autumn, which may be caused by the abnormal large amount of rainfall in autumn. （4） The negative oxygen ion concentration shows a slight declined tendency in the Dalaoling forest area，and that shows a contrary tendency in typical urban areas. （5） In urban areas, the daily average concentration of negative oxygen ions is higher in foggy days and rainy days than those in thunderstorm days and overcast days，and the minimum is found in sunny days. On the contrary, in forest areas, the daily average concentration of negative oxygen ions is higher in sunny days and thunderstorm days than that in overcast days, and the minimum appears usually in rainy days and foggy days.
