Abstract: The effects of lead concentrations (500, 1 000, 1 500 mg/L) on the antioxidant enzymes (SOD, POD), cell membrane (MDA, the relative conductivity) and osmoregulation substances (soluble sugar and proline) in the leaves of perennial ryegrass (Lolium perenne) were studied after different stress durations (7, 14, 21, and 28 d) in a pot experiment. SOD activity increased initially and then decreased with the increase in lead concentration. At lower concentrations (500, 1 000 mg/L) and shorter durations (7, 14 d), SOD activity significantly increased but then declined rapidly. POD activity decreased significantly with increases in stress duration and lead concentrations. POD activity was minimum (45.9 U/g) at the 28th day and 1 500 mg/L of lead. With increases in stress duration and lead concentrations, MDA content and the relative conductivity generally increased. MDA content was positively linearly correlated with lead concentration (R²>0.96). Soluble sugar content showed complex change trends, and tended to reduce at the higher concentrations and longer durations. Proline content significantly increased at the lower lead concentrations. If lead concentration exceeded the limit of perennial ryegrass tolerance, proline content would decline. It indicated that perennial ryegrass can be tolerant to lead stress but there is progressive damage under the stress.