Using rape as materials,effect of simulated acid rain of pH5.2 and six different levels of Pb,Cd on the activity of cell defense enzymes system,leaf chlorophyll content,germination rate was studied.The results showed that when Pb and Cd was less than 100mg/L,total length of seedlings,weight of seedlngs and weight of roots were decreased as stress increased.The activities of SOD,POD were increased at first and decreased later.However,their activities were higher than that of control.Activity of CAT was increased all time.Germination rate was increased when heavy metal elements were low,but decreased when heavy metal elements were higher.When the levels of Pb and Cd was less than 5mg/L,leaf chlorophyll content was increased,but it was decreased when the levels of Pb and Cd was more than 5mg/L.Chlorophyll a/b was also increased at first and decreased later.