Based on the data of 60 plots obtained from investigation,the niche breadth and niche overlapping of 13 main herbage populations in Eucalyptus grandis plantation were studied by using Levins and Shannon-Wiener niche breadth index and Levins niche overlapping index.The niche breadths of Hicriopteris glauca and Miscanthus sinensis were bigger than that of the others because these two species had extensive adaptation to environment.The species with big niche breadth didn’t always have big niche overlapping,and the niche breadth and niche overlapping did not have a positive direct liner relation.In conclusion,relatively lower niche overlapping between species were apparent in herb layer of E.grandis plantation.From the eco-response rate,aggression of H.glauca was strongest,and few species would monopolize the herb layer of E.grandis.