Density and nutrient level are important factors that might affect the growth of invasive plants.To reveal the effects of plant density on the performance of invasive plant Alternanthera philoxeroides under different nutrient conditions,a greenhouse experiment was conducted in which A.philoxeroides was planted at three densities(low,medium and high)under three nutrient levels(low,medium and high).The results showed that both planting density and nutrient levels had significant effects on the growth of the plant.