Abstract: Using the hourly data of air pollutants in Dongying city from 2014 to 2019 and precipitation, pH and conductivity (K) of acid rain samples from 2006 to 2019, the variation characteristics of air quality index (AQI), main pollutants IAQI and acid rain were analyzed, and the correlation between AQI and acid rain pH and K was studied. The results showed that: 1) The air quality excellent rate increased from 44.38% to 78.99% in 2014-2019, and the weather was dominated by fine weather. AQI was generally in a downward trend, the main pollutants were PM₁₀ and PM_2.5, and SO₂ was in an obvious downward trend, indicating that the local treatment effect of coal and industrial sources was significant. However, O₃ rising trend was prominent, which indicated that O₃ may become an important source of air pollution. 2) Dongying City belonged to the light acid rain area, which was gradually changing from sulfuric acid-nitric acid type to nitric acid type and compound type. The mean value of pH was 5.41, and the mean value of K was 113.2 μS/cm. The annual mean value of pH was between 4.87 and 5.79, showing a curve upward trend, and the annual mean value of K was between 76.9 and 162.0 μS/cm, showing a general downward trend. The frequency of heavy acid rain was obviously decreasing, showing that the local air environment management had been effective. 3) Dongying City had a non acid rainy season in spring, with the lowest K in summer and the largest in winter. The maximum value of monthly precipitation pH and the higher value of K appeared in March, which was due to the inversion layer and decrease of coal sources in heating period, the dry and windy weathers, the increase of local alkaline dust, the decrease of precipitation, the slow process, the constant adsorption of pollutants in the air, leading to the increase of K, and the neutralization of precipitation pollutants and alkaline dust, leading to the increase of pH. The minimum average value of K and the smaller value of pH appeared in August, which indicated that the pH of precipitation was in direct proportion to AQI and had little relationship with precipitation in May to August when precipitation was concentrated; K was in direct proportion to AQI and was in inverse proportion to precipitation. 4) The pH of precipitation had a significant correlation with AQI of the previous day, while K had a significant correlation with AQI of the current day. 5) In 2019, AQI did not change compared with 2018, but NO₂ increased compared with 2018, and K increased significantly. Weak acid and weak acid precipitation showed an upward trend from 2018 to 2019, which showed that the environmental governance needed to continue to make efforts in the region.