Abstract: Negative air ion is good to people’s health and is an important resource in tourism region. Status o[ negative air ion in forest environment has become the issue of the day in re cent years. This paper reviewed the negative air ion formation mechanism, its functions on organisms and environment, and the contents, influence factors and spatio--temporal change characteristics of negative air ions in forest environment. Highlights were given to measuring devices, research method, and evaluation criteria, daily and seasonal change of negative air ion, and effects of forest stand, weather condition and water body on forest negative air nion. The main prohlems in the past work and the direction for the future research were also discussed.