Wetlands in northern China are complex ecosystems composed of grasslands, lakes, rivers and swamps, which have immense ecological values. When a highway system passes through a wetland, it has adverse effects on its ecosystem. However, in many cases, it is difficult to avoid a highway system pass through a wetland. Taking the Erka wetland in northern China as an example, nine survey lines, perpendicular to the highway, were set up. According to the distance from the highway, the plant multi-element information was collected. After the analysis of plant growth habits, spatial characteristics and profile features, the following four conclusions were drawn: (1) the highway system divided the plants habitat and made the vegetation communities on both sides develop anisotropically; (2) the highway system interfered with the interspecific competition of the nearby plant populations, making it easier for the plant communities with fast propagation speed, drought resistance and anti-interference to establish advantages; (3) the plant growth within 80 m of the highway was inhibited and (4) the wetland plant community succeeded to grassland plant community. In order to reduce the adverse impact of highway system on wetland ecosystems, it is suggested that in the follow-up highway upgrading project, either diversion of highway or construction of bridge or culvert excavation should be considered.