Abstract: In this paper, the generating capacity of negative air ions from plants was studied under the conditions of different environmental elements such as air relative humidity, temperature and illumination intensity. The results showed that the capacity of individual plant to generate NAI is very weak in natural condition. However, the ability of plants to release negative ions was significantly enhanced by impulse electric field stimulation (P<0.05). Under the stimulation of pulsed electrical field, the capacity of the plant to release negative ions was close to the level under natural condition when the humidity was 20%, and this capacity continuously enhanced with the increase of humidity. Similarly, the greater light intensity, the stronger releasing ability of plants negative ions. And the effect of the temperature on NAI generation was the weakest,and the ability to release negative ions is inhibited only at a condition of lower temperature (5.0℃).