Abstract How the traits of invasive plants determine their invasiveness is one of the major issues in invasion biology. Invasive plants usually have broad ecological amplitudes, and hence can exploit a great diversity of habitats. Genetic differentiation and phenotypic plasticity are two major strategies that invasive plants can use to invade broad geographical areas and diverse ecosystems. Phenotypic plasticity is a trait that has a certain genetic basis and can evolve independently. Although some of the invasive plants have low genetic variation, they can still invade diverse habitats. Phenotypic plasticity may play a critical role in invasion of these species into new environments. In this review, the concept of phenotypic plasticity and its significance for adaptation were introduced. The relationship between phenotypic plasticity and the invasiveness of alien plants was discussed, supported by theoretical analysis and published experimental evidence.We also suggest some issues that might be addressed in future studies for better understanding of the mechanisms of successful invasion with reference to phenotypic plasticity. Although successful invasion cannot be explained by phenotypic plasticity alone, the positive correlation between invasiveness and phenotypic plasticity seems to be a rule rather than an exception for those invasive species with low genetic diversity but a broad geographic distribution.