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In order to better consolidate the results of the creation of “China’s Natural Oxygen Bar” in Yichun, promote the green and healthy development of Yichun’s forest recreation and tourism industry, and help transform the value of ecological resources in the Lesser Khingan Mountains region, this paper formulates a data quality control method to analyse and evaluate the characteristics of the daily changes of anion concentration in the hinterland of Yichun based on the monitoring data on the anion concentration in the air at 13 stations in Yichun. The annual, seasonal, monthly and diurnal variation of anion concentration in Yichun, the hinterland of the Lesser Khingan Mountains, are analysed and evaluated. The results show that the annual average negative oxygen ion concentration in Yichun is generally higher than that in most areas in China, showing a spatial distribution of high in the mountains and low in the plains, and increasing with the latitude and longitude and the forest cover, showing a growing trend from the south to the north. Seasonal change characteristics are not significant; the overall trend is the highest in summer, followed by winter and spring, and the lowest in autumn, while the counties and districts show obvious local characteristics. Negative oxygen ion concentration has a daily change pattern, showing U-shaped bimodal characteristics, with nighttime significantly higher than daytime. Monthly changes are not significant, with the peak occurring in July-August and the lowest values in January and April. Negative oxygen ion concentrations in 90 percent of the county-level administrative areas reach the level of Class I, and the negative oxygen ion concentrations at the three types of monitoring stations basically reach the level of freshness and above.