To study the effect of construction dust and agricultural fertilization on the chemical composition characteristics of precipitation during the summer in the Yangtze River Delta region (China), the chemical composition of 144 precipitation samples collected at Wuxi from June 6th to July 15th in 2016 was analyzed. The results demonstrated that the pH values varied from 4.72 to 7.08 for all the precipitation events sampled, with the average pH value as high as 5.88. More than 68% of precipitation events showed pH values higher than 5.6, indicating lower acidic characteristics. The concentrations of anionic ions followed the order of SO₄²⁻ > Cl⁻ > NO₃⁻ > F⁻ > NO₂⁻, indicating SO₄²⁻, Cl⁻ and NO₃⁻ were the main anions. The concentration of cationic ions followed the order of Ca²⁺ > NH₄⁺ > Na⁺ > Mg²⁺ > K⁺, indicating Ca²⁺ and NH₄⁺ were the main cations. The construction dust and agricultural fertilization were responsible for the increase of Ca²⁺and NH₄⁺ concentration. Significant correlations between NH₄⁺ and SO₄²⁻ were found, indicating the neutralization ions and combination of all acidic had a great influence on acidity. The higher pH value could be attributed to the neutralization by the high concentration Ca²⁺, which is proven by the neutralization potential and acidic potential. The average value of fractional acidity is 0.28, indicating approximately 72% acidity is neutralized by alkaline composition. The influence of anthropogenic sources was dominant in chemical composition, higher than the marine and crustal source.