Abstract: Recent progress in studying mechanisms of biological invasion is reviewed involving several aspects , such as biological characteristics of exotic species , interaction among exotic species and their new neighbours , the relationships between species diversity and community resistance to invasion , the effects of changing ecological factors in new habitats. We also analyze the progress of research methodologies and some unsolved vague points in this field. According to recent studies , the mechanisms of biological invasion seem so diverse that no common pattern could explain all cases. A better understanding of invasive mechanisms is essential in developing ecological theory and significant in cont rolling exotic pests.