In this paper a new 5 chloro salicylaldehyde ureidoamine Schiff base ligand and its complex containing Mn(Ⅱ) and Co(Ⅱ){·2H2O,·2H2O,[Co(HL)(NO3)2]·2H2O,·2H2O} were synthesized by the condensating 5 chloro salicylaldehyde with semicarbazide.Its compositions and structure have been characterized by he ele mental analyses,thermal analyses,IR spectra and UV spectra.The free radical inhibition rate to O2- have been tested.