To study the characteristics of heavy metal enrichment and migration affected by Spartina alterniflora invasion in coastal wetland and provide a scientific basis for the ecological protection and rational utilization of the coastal wetland, three sampling sites with different invasion years of Spartina alterniflora were selected, and the heavy metal contents of Cu, Zn, Pb and Cd at 5 cm intervals in 0 - 30 cm sediments and Spartina alterniflora were analyzed and evaluated using geo-accumulation indexes, potential ecological risks evaluation methodology, bioconcentration factor and biological translocation factor. The results suggested that: the contents of Cu, Zn, Pb and Cd in sediments were 5.94-31.94 mg(kg^-1, 18.59-56.87 mg(kg^-1, 4.76-30.36 mg(kg^-1, 0.021-0.083 mg(kg^-1, respectively, lower than the environmental background values in the study region; the contents of Cu and Pb showed mild pollution in 0-15 cm sediments; the contents of heavy metals in vegetation areas were higher than those in bare flat areas, particularly in the upper level (0-15 cm). The preferential order of contents of heavy metals in different parts of Spartina alterniflora was root > leaf > stem; the preferential order of enrichment effect of heavy metals in the root was Cd > Zn > Cu > Pb; the preferential order of transport efficiency was Pb > Zn > Cu > Cd. The change of the physicochemical properties of the wetland deposits was an important reason for the accumulation of heavy metals in the sediments. The differences in migration and transport of heavy metals in the sediment-plant system were mainly related to the absorption of heavy metal elements in different parts of Spartina alterniflora.