Abstract: The researches about reed (Phragmites communis) growth were mainlyconcentrated on seasonal dynamics, investigation of large area resource, and comparison of different ecological forms of reed. The study on size distribution of reed,however, was scarcely reported. By means of fractal geometric theory of non-linear science, we studied the fractal character of growth pattern of reed, for the purpose of quantitatively exploring the mechanism of reed growth. The classical method of studying size distribution is to draw histogram and then to fit distribution curve. It is well known, however, that the obtained histogram is strongly depended on the number of class interval and its correspondent width. The determination of rational number and width of class interval is somewhat arbitrary, since it is gotten according to analyst’s experience. In general, there are a certain similarity among histograms described at different class number of class interval and width somehow. It implies that we could use the fractal geometry to analyze the relationship among them, and reach more reliable conclusion.The data we used in our analyses is from the monthly sampling in Caogang Lake (114°E, 35°N), an emergent macrophyte dominated lake in Fengqiu Experimental Area of the Huanghuaihai Plain, Henan Province, P. R.China The way to calculate fractal dimension (FD) of reed growth is box-dimension (BD) and information dimension (ID).Because the longest reed occasionally exceeds 400 cm, for the reason of convenience,we define the largest scale S=400 cm. Halving the scale S until it could recognize each individual reed (S0.8), but is irregular in the middle and later growth season (fractal dimension<0.7). These results are benefit to reach the goal of rational use of reed resources and to protect the biodiversity in wehand ecosystem.