Abstract: Bryophytes are a group of plants considered to be sensitive indicators of air pollution.Hypnum has been widely used to monitor air pollution across the world.To better understand the response of moss to heavy metal stress,the contents of chlorophyll,proline,malonaldehyde(MDA),and soluble sugar of Hypnum plumaeforme under different concentrations of Pb were analyzed.The results showed that chlorophyll content of H.plumaeforme increased under low concentration of Pb(<0.01 mmol/L),but decreased under high concentration of Pb(≥1 mmol/L).The contents of proline,malonaldehyde(MDA),and soluble sugar increased slightly under lower concentration of Pb(≤0.1 mmol/L)and increased significantly under higher concentration of Pb(≥1 mmol/L).The results indicated that the moss reacted to Pb stress well to protect itself.Analysis of linear regression results showed a good dose-effect relationship between the four physiological indices and the different concentrations of Pb.