Using FTP-2-type air ion measuring instrument, the air positive and negative ions concentrations in Shennonggu National Park were measured, the observation data was handled and analyzed. The results show that (1)The negative air ioia concentration of the main measuring point of Curtain Fall of Shennonggu was 4 555/cm^3, more than that of Ox Horn Ridge 2 379/cm^3; (2)Water had a great impact on air negative ion level in forest environment; (3)Negative air ion concentration also presented a certain daily, monthl...