Abstract: The precipitation chemistry over China had been studied on a nation-wide monitoring network from 1991 to 1995. Precipitation samples and other meteorological data were collected at the National Acid Deposition Monitoring Network with 271 sample sites over the country. Precipitation pH and electro-conductivity were measured in the field and the chemical analysis of collected samples were conducted in the laboratory. The annual precipitation weighted concentrations of SO^2-₄, NO^-₃, NH⁺₄ and Ca²⁺ are 125.86, 19.62, 67.89 and 80.41μeq/L, respectively. The geographical distribution of these ion concentrations in precipitation shows that the scenarios vary from ion to ion. It is interesting to point out that the SO^2-₄ concentrations in the northern non-acid rain areas are generally much higher than that in the southern acid rain areas. It means that the rain acidity is not only determined by the absolute concentrations of SO^2-₄ and NO^-₃, but by the relative concentration of basic and acid ions in precipitation. It is found that the rain pH has a minimum annual average value which is lower than 4.0 in some areas, and it is probably the lowest pH in precipitation in the world. The characteristics of chemical deposition of rain water for typical areas were analyzed, and results showed that the rain acidity is still increasing over China.