Abstract: We used the fractal geometric theory of non-linea r science, studying the fractal character of the horizontal pattern of Ass.Nelumbo nucifera in Baoan Lake. Methods used to calculate fractal dimension valu es are box-dimension and information dimension. The results showed that the diff erence between in two macrophytes' the distribution of the association. Nelumb o nucifera was the dominant species in August. It was demonstrated that the bo x dimension of distribution of Nelumbo nucifera was 1.92, information dimens ion was 1.88; the box dimension of distribution of Trapa insica was 1.04, in formation dimension was 1.11. This result showed Nelumbo nucifera uniformly distributed at the given scales from 0.5m to 8m. The variety of the fractal dimen sion of Nelumbo nucifera in the sequent samples was discussed.