Abstract: In order to reveal specifically the impacts of Trifolium repens L. on lawn species and biodiversity of manila lawns, a study was carried out in Quzhou city, Zhejiang province from 2009 to 2011. Two manila lawns were monitored under the site conditions,one with Trifolium repens L. planted and one without. Through the community ecology research method, items such as the height, number and density of weed species were examined. The research showed that significant differences(p<0.05)could be observed:(1)weed species from 2009 to 2011 were 35, 29, 22(with Trifolium repens L.)and 47, 51, 52(without Trifolium repens L.), respectively;(2)Shannon diversity index(H’), Shannon evenness index(E)and Margalef species richness index(D_MG)were 4.97, 1.30, 0.42(with Trifolium repens L.)and 10.17, 2.38, 0.83(without Trifolium repens L.), respectively. The findings revealed that the invasive weed Trifolium repens L. had significant influence on both weed species and diversity. It was then strongly recommended that invasion of Trifolium repens L. in lawns should be under strong supervision and control and the practice of growing Trifolium repens L. as an ornamental plant in lawns should not be encouraged.