The aero-anion concentrations above the different function areas in Xiamen city were measured to analyze not only the relationship between the aero-anion concentrations and vegetation but also the relationship between the diurnal variation pattern and temperature and relatively humidity (RH).The results indicated that the air quality was in order of large scale arboretum and park >uptown >sowntown >beach >industrial park >piazza.The aero-anion concentration was higher during night time than during day time.Over a whole day its maximum appeared in wee hours, and the minimum in noontime.The aero-anion concentrations felled with the temperature rising and rose with the relative humidity (RH) increasing.