Abstract: Several sites were selected in 2009-2010 to measure the negative air ion concentration in Laojun Mountain. The results showed that the daily process of negative air ion concentration shows different curve at different biotopes, showing that moving water and its surroundings > forest stand > stationary pond, but there was no significance among forest stands. The higher of waterfall dropped the larger distance affected by waterfall, the concentration reached maximum around the stand edge. There was significant difference at different elevation, and reached maximum at about 1500m, but there was no significance among similar biotopes at similar elevation. Many regression models could be used to simulate the relationship between negative air ion concentration and biotope, but only restricted to certain site and time.