In order to provide a theoretical basis for “plant sources of negative ion generator”,this paper explores the effect of CO2 and light on the releasing negative air ion （NAI）of Agave americana through study on the NAI level produced by Agave americana under highvoltage pulsed electrical stimulation.NAI Produced by Agave americana, CO2 concentration and light intensity in the fabricated organic glass enclosure（2.5 m× 2.0 m×3.0 m）under highvoltage pulsed electrical stimulation between light and dark are determined and compared.The results show that Agave americana can generate more NAI under highvoltage pulsed electrical stimulation with light and the daily variation of NAI is obvious; There aren’t significant correlations between the NAI levels produced by Agave americana under highvoltage pulsed electrical stimulation and the indoor CO2 concentration, but the NAI level hs significant binomial correlations with light intensity.