23 samples were collected at the summit of the Mount Taishan from July to December in 2004. The precipitation pH value, electrical conductivity and major water-soluble ions were measured and back trajectories of precipitation events were analyzed. The results showed that the volume-weigh pH value of the samples was 4.74, the volume-weigh electrical conductivity was 2.26 mS·m~ -1 which proved that the precipitation at the Mount Taishan has been acidified seriously. The concentrations of ammonium, calcium, su...