Abstract: ObjectiveSalt tolerance of Brassica oleracea var. acephala f. tricolor after being transferred with △1-pyrroline-5-carboxylate synthetase(P5CS1) gene from Arabidopsis thaliana was analyzed, in order to obtain slat-tolerant B. oleracea var. acephala f. tricolor varieties and provide reference for breeding for stress tolerance. MethodP5CS1 gene from A. thaliana was transferred into B. oleracea var. acephala f. tricolor via Agrobacterium. Under salt stress,expression of P5CS1 mRNA, proline content in seedlings, root traits, dry weight of whole plant,fresh weight of whole plant,relative wa-ter content in leaf, relative electric conductivity of leaf and whole plant survival rate in transgenic plants and wild plants were measured. ResultUnder 150 mmol/L NaCl stress, P5CS1 mRNA of transgenetic plants was in normal expression. Compared with control, main roots and the longest lateral roots of transgenic plants Y1 and Y2 were long, lateral roots were abundant, dry weights and fresh weights of whole plant were heavy. Their relative water contents were significantly higher than that of control(P<0.05, the same below), proline contents and survival rates were extremely significantly higher than that of control(P<0.01), but relative electric conductivity of leaf was significantly lower than that of control. ConclusionSalt tolerance of plants genetically modified by AtP5CS1 was better than control. AtP5CS1 gene expression significantly im-proves salt tolerance of transgenic plants in B. oleracea var. acephala f. tricolor.