Abstract: The issue applied the fractal theory to study th e character of dominant macrophytes' leaves in Baoan Lake of Hubei Province. The leaves are the most representative modules, and many scientists study the mo rphology of them. The leaves of macrophytes are the main organs that participate the photosynthesis in the water. The leaf numbers, the leaf surface and spatial pattern of them directly influence the illumination intensity and spectrum comp onent, which affects the plant's utilization efficiency of light. By introducing the Box-counting dimension (self-made software), one method the fractal theor y provided, the scanned photos of leaves were treated. The fractal dimension (FD) ofPotamogeton malaianus leaves was between 1.322 and 1.520,with an ave rage of 1.441,and a standard deviation of 0.0547. The FD ofPotamogeton cri spus leaves was between 1.381 and 1.565,with an average of 1.472,and a standard deviation of 0.0489 . The FD of Najas marina leaves was between 1.209 and 1.406,with an avera ge of 1.325,and a standard deviation of 0.0547. The FD ofHydrilla verticil lata leaves was between 1.001 and 1.217,with an average of 1.103,and a standard deviation of 0.0456. The FD ofCeratophyllum oryzetorum leaves was between 1.221 and 1.542, with an average of 1.442,and a standa rd deviation of 0.0862. By compared with the morphological differences among their leaves, we can well realize the ecological meanings of the fractal dimensions (FD) calculated. The sequence of average FD of leaves was:Potamogeton crispus>Ceratophyllum oryzetorum>Potamogeton malaianus>Najas marina>Hydrilla vert icillata, which indicated the difference in the ability of spatial occupying a nd utilizing among different species' leaves. The t-test for fractal dimension of 5 macrophytes' leaves showed that there are no significant differences betwe enPotamogeton crispus, Ceratophyllum oryzetorum andPotamogeton malaianus, which could be caused by the reasonPotamogeton crispus andPotamogeto n malaianus belonging toPotamogetonaceae. The t-test also showed that t he leaves ofCeratophyllum oryzetorum have a spatial pattern more similar to them. The work well describes the morphology of different species' leaves in qu antity. It will benefit realization of the macrophytes’ adaption to water body, and provide the basic information for our further study on the macrophytes patte rn at large scale.