Abstract: The change of the internal physiological characteristics of four species in genus Lysimachia under low-temperature stress was studied to explore the damage mechanism of the low temperature by taking leaves as experimental materials.The results showed that the low-temperature stress treatment resulted in membrane damage and the increase of membrane permeability of leaf cells;the activities of SOD and POD increased at the beginning and declined afterwards.The contents of proline,soluble sugar in the leaves increased to a certain degree under low-temperature stress,the changes differed in amplitude and procedure.It was concluded through comprehensive analysis of these physiological and biochemical characteristics that the cold resistant ability of the four species in genus Lysimachia decreased in the order of L.alfredii,L.nummularia 'Aurea',L.christinae var.huaye and L.congestiflora.