Abstract: There were 346 species belonged to 100 families by the investigation on plants in different crab-raising areas in Nanyi Lake, of which 49 species aquatic vascular plants accounted for 35.2% of aquatic vascular plants in Anhui Province and 25 families accounted for 69%.The diversity was distinct lower. The plant associations were also obvious unlike in different cultivated areas. The association was single, where Vallisineria spiralis L. and Hydrilla verticillata (L.F.) Royle exist in pen crab-farming zone and the companion species were distinctly more simple than ones in other zones. There were exotic species Eichhornia crassipes (Mart.) Solms-Laub and Alternanthera philoxeroides (Mart.) Grisb in pen aquaculture aera, which affect ecological development. The results showed the diversity of aquatic vascular plants in pen crab-farming zone was beyond 0.5; the crab-farming zone without nets was 0.6-0.7 and the non-aquaculture zone was above 0.8.