Abstract: Based on the the East Mountains Forest Farm in Taiyuan air negative oxygen ion concentration real-time monitoring and data analysis. The results showed that: the number of negative air ions in different season was showed as different. The number from high to low was arranged as in summer, in spring, in autumn and in winter. The three monitoring points obviously showed that the closer to the water edge, the higher the canopy density, the higher the concentration of negative oxygen ions. The number of negative air ions in different weather was different, the concentration of negative oxygen ions in rainy days is obviously higher than that in sunny days.