Abstract: This experiment was conducted in Hailun Agriculture Ecological Experiment Station in northeastern China,CAS, since 1991, with site specific different rotation systems including continuous corn (C-C-C……C),corn soybean corn(C-S-C),and rotation(soybean wheat corn,S-W-C).The results showed that the weed density and weed fresh weight were the least in CSC .In different years, the weed population were different at the same plots .Weed species were more in C-C-C……C plot than in S-W-Cand C-S-C plots.For example, Kummerowia stipulacea only occured in C-C-C……C plot but did not occur in S-W-C and C-S- C plots in 2000.Malachium aquatium only appeared in C-C-C……C plot but did not occur in S-W-C and C-S-C plots in 2002.Some weed population appeared in C-C-C……C except C-S-C and S-W-C.But in some year, some weed disappeared in C-C-C……C.

Key words: Stand condition improvement, Dendrocalamus latiflorus, Hilly land, Nutrient loss