For plants,leaf is an important organ to obtain resources . It is conducive to understanding the biological invasion mechanism by exploring the relationship among leaf functional traits and responses to environmental factors.In this study, we measured 14 leaf functional traits and 10 environmental factors (light intensity, air temperature and humidity, soil physical and chemical properties) of Bidens alba with 3 invasion levels (mild invasion, moderate invasion, severe invasion). By one-way ANOVA, correlation analysis, redundancy analysis and other methods, we analyzed the resource allocation pattern, absorption and utilization strategy in the process of invasion.The results showed that: (1) Leaf width, leaf area, leaf dry weight, leaf dry matter content and leaf total phosphorus content increased significantly with the increase of invasion degree. There were the highest specific leaf area and leaf total nitrogen content under moderate invasion. There were the lowest Leaf thickness, leaf volume and fresh weight under moderate invasion. (2) There was close relationship among leaf functional traits. In mild invasion degree, leaf length was observably correlated with leaf width and leaf area. Leaf fresh weight was observably correlated with leaf dry weight. There was significant correlation between leaf total nitrogen content and leaf total phosphorus content under moderate invasion. The specific leaf area was significantly correlated with leaf dry weight, leaf dry matter content and leaf tissue density under severe invasion. (3) Redundancy analysis showed that light intensity, soil humidity were the main factors affecting the invasion of Bidens alba. Leaf length, leaf area, specific leaf area, leaf total nitrogen and leaf tissue density increased with the increase of temperature. Leaf dry matter content and leaf thickness increased with the increase of light conditions. Leaf tissue density decreased with the increase of air humidity. In summary, in the process of mild invasions to moderate invasions, Bidens alba tended to adopt acquisition strategy (high input - low return). But in the process of moderate invasions to severe invasions, its strategy turn to resource conservation strategy (low input - high return).