167species exotic weeds belonging to 28 families were identified and recorded through re-survey of all over twenty-five provinces and referring to the related literatures up to 2003. Among those originating from all five continents in the world, the exotic weeds introduced from America accounted for 57.48％. 67.67％ exotic weeds were introduced as useful plants for ornamental, medicinal, forage, vegetable, environmental utilization, while the others were introduced accidentally in accompany with transportation, imports of agricultural products or invaded by natural spread. The analysis of introduction time indicated that invasion of the exotic weeds had been occurred since ancient times, and invasion incident augmented from ancient time 18.56％ to current time 56.29％ as the international exchanges increase. The most dangerous invasion weeds of China were Alternanthera philoxeroides, Eupatorium adenophorum, Ambrosia artemisiifolia, Eichhornia crassipes, Eupatorium odoratum, Conyza canadensis, Erigeron annuus, Conyza bonarinsis, Spartina alterniflora, and Ageratum conyzoides; and potentially dangerous ones Sorghum halepense, Mikania micrinata, Solidago canadensis, Lolium temulentum, and Ambrosia trifida. The distribution of the exotic weeds in China was governed by the integration of the inherent ecological adaptability of the weeds, their spread capability and the human spread activities.