Abstract: By carrying out the macrophyte biomass investi gation in 1996, we got the annual production of dominated species in Baoan Lake. The Decomposition experiment of dominated species had been done in the lab. On the basis of considering carbonaceous content in the dominated species and the d ynamic of DOC and POC in the water, we elucidated the function of macrophyte in the carbon circulation of Baoan Lake. We also use the fractal geometry and geost atistical analysis to study the pattern of carbon in the macrophyte on a lake sc ale.