Abstract: Weed damage is one of the main contradictions in the field of perenial upland rice. The field survey showed that, there are 98 weed species, 22 families in the field of perenial upland rice. Of these, 7 species are the main weeds, including Solive anthemifolia R. Br. ,Allernanthera philoxeroides (Mart.) Griseb. , Centella asiatica (L.) Urban, in spring and Eleusine indica(L.) Gaertn, Kyllinga brevifolia Rottb. ,Juncellus serotinus (Rottb.) C. B clarke and Cynodon dactylon (L.) Pers. in autumn. Four green manures were used to control the weed communities at four periods in the upland rice fields. The statistical analysis on the relationship between four growing-manners of green manures with biomass amounts of weeds showed that the growth of green manures has an effective weed-depressing effect. The seed drops of Austragalus sinicus, Kummerowia striata and Lespedeza davidii naturally formed a community of green manure in 1991 , which depressed and replaced the original weeds in the fields of perenial upland rice. Green manures can also increase the manure efficiency, regulate the temperature, thus inprove the growth of perenial upland rice.