Based on the chemical composition of precipitation data in Waliguan from 2007 to 2009, the pH value, conductivity and distribution characteristics of Cl^-, NO₃^-, SO₄^2-, NH₄⁺, K⁺, Na⁺, Ca²⁺ and Mg²⁺ are analyzed.Results show that the annual mean of pH and conductivity are 6.60 and 21.26 μs/cm, respectively, and they have rising trends from 2007 to 2009.In terms of the pH value, the frequency of neutral-based precipitation is the most(65.13%), followed by the alkaline precipitation, and the acid rain is the least.The ion concentrations from high to low are Ca²⁺, SO₄^2-, Na⁺, NH₄⁺, Cl^-, Mg²⁺, NO₃^- and K⁺, respectively, which have obvious seasonal variations.The K⁺, Na⁺, Ca²⁺, and Mg²⁺ have similar sources.The value of SO4^2-/NO^3- in the precipitation varies from 0.35 to 16.48, and the mean value is 3.07.The value of SO4^2-/NO^3- has a falling trend from 2007 to 2009.The annual variation of SO4^2-/NO^3- has two peak values in April, and September-October, respectively.