Abstract: This paper summarized the relationship between acid rain and death of Pinus armandi.In severe affect areas of Liziping Forest Farm,Wushan County,the average acidity in the rain per month,from May to August were pH 6.06,5.80,6.05 and 5.78 respectively.Experiments were conducted by simulation testing,spraying diluted sulphuric acids in pH 3.5,4.5 and 5.5 on the trees.Results showed that there were no harmful effects either on growth,dry weight or chlorophyl contents of P.armandi.It demonstrated that so called'acid rain' was not the causal agent responsible for the death of trees in vast eastern mountainous area 1600m above sea level in Sichuan Province.