A hydroponic experiment was adopted to investigate variations in membrane permeability, chlorophyll content, antioxidase activity, ascorbate (AsA)-glutathione (GSH) cycle, and glyoxalase system in leaves of Pontederia cordata with 0-15.0 mg L-1 Pb2+ concentration exposure. No obvious variations in cholophyll, ascorbic acid (AsA), dehydroascorbic acid (DHA), glutathione (GSH), non-protein thiol total peptide (NPT), and phytochelatins (PCs) contents, and catalase (CAT), superoxide dismutase (SOD), and ascorbate peroxidase (APX) activities were detected in the plant leaves with 5.0 mg L-1 Pb2+ exposure for 14 d and 21 d. And meanwhile, the treatment of 5.0 mg L-1 Pb2+ exposure for 21 d increased methylglyoxal (MG) content, while MDA content in the leaves did not show a significant increase. With 10.0 mg L-1 Pb2+ exposure for 21 d, the contents of MDA, MG, GSH, and NPT, as well as POD activity in the leaves markedly increased, and an opposite trend was demonstrated in monodehydroascorbate content was noticed, and correspondingly GSH, NPT, PCs were synthesised to chelate exccesive Pb2+ accumulated in the leaves, and meanwhile POD, SOD, and APX activities and AsA content were also stimulaed to alleviate oxidative damage induced by Pb2+. Increased MG content and decreased GlyⅡ activity were found inspite of increased glyoxalase I (GlyI), indicating glyoxalase system can not effectively cope with carbonyl stress induced by the 15.0 mg L-1 Pb2+ exposure treatment. The leaves of P. cordata exhibited a good tolerance to 5.0 mg L-1 Pb2+ exposure. The stimulated non-protein thiol compound synthesis, antioxidase activities and AsA content were employed to mitigate oxidative damage induced by Pb2+ concentrations no less than 10.0 mg L-1. Glyoxalase system in leaves of Pontederia cordata did not represent an markedly detoxification as expected.