We surveyed occurrence of three emergent alien aquatic plants, including Gymnocoronis spilanthoides, Alternanthera sessilis, and A. philoxeroides in Lake Kasumigaura from 2013 to 2017. To test the effects of shoreline modification on the expansion of alien aquatic plants, we compared the relative occurrence of alien aquatic plant in the groups of varying shoreline conditions modified by shoreline hardening and wave breakers. The distribution of alien aquatic species kept increased in Kasumigaura, though the rate of expansion was different among the years. And more than 64.6% of the floating fragments was founded within the 2km from the nearest patch. We found that construction of wave breakers have a positive influence on the patch density of alien aquatic plants. Especially, wave breaker with parallel type increased the patch density of G. spilanthodies about 2.27 times compared with the natural condition. Wave breaker with perpendicular type increased the patch density about 1.63 times. It is important to consider the lakeshore management to combine suppression of alien plant and levee protection. And we suggest prompt action to prevent the expansion of alien aquatic species around the pumping stations, which can further result in relocation of invasive species.