In order to explore the phenotypic variations and adaptive strategies of invasive Galinsoga parviflora in different microhabitats. The G. parviflora populations growing along the playground, rdump, green belts, uncultivated land (abandoned farmland), orchard, and kerbside were selected. Phenotypic traits related to growth and defense were analyzed using methods such as one-way ANOVA, multiple comparisons, principal component analysis, and cluster analysis. The results of one-way ANOVA and multiple comparisons showed that there were statistically significant differences ( p ＜005) in traits reflecting growth status, such as plant height, leaf number, and inflorescence number, among G. parviflora populations in different microhabitats. There were also statistically significant differences ( p ＜005) in traits reflecting defense status, including the contents of flavonoids, total phenols, condensed tannin content, and leaf trichome density, among the G. parviflora populations in different microhabitats. The content of total phenols, flavonoids, and condensed tannins in the leaves and inflorescences of G. parviflora growing along the playground was higher, and the leaf trichome density was the largest. In contrast, the content of total phenols, flavonoids, and condensed tannins in the leaves and inflorescences of G. parviflora growing in the dump was lower, and the leaf trichome density was the smallest. The biomass of G. parviflora in the dump was the largest, while the biomass of G. parviflora along the playground was smaller. The coefficient of variation of phenotypic traits of G. parviflora in different microhabitats was high, with the maximum average coefficient of variation being that of petiole length and the minimum being that of plant height. The results of principal component analysis showed that the first principal component was mainly influenced by traits related to biomass, while the second principal component was mainly influenced by defense traits. Cluster analysis revealed that the G. parviflora population along the playground clustered into one group, while the other five populations clustered into another group. These results indicate that G. parviflora populations can exhibit high phenotypic variation in growth and defense traits within a small spatial range. G. parviflora adjusts resource allocation between growth and defense according to different habitat conditions, and populations in different microhabitats have different defense strategies. These characteristics promote the successful invasion of G. parviflora into various habitats.