[Objective]To understand the invasion mechanism of the invasive plant Salvia tiliifolia. [Methods]The differences in growth, reproduction, and defensive traits between S. tiliifolia and the cultivated S. splendens were studied under different fertilization conditions. [Results]Except for root dry weight and height of S. tiliifolia, biomass of both plants significantly increased under high-fertilization conditions compared to the control. The flower flavonoid and tannin contents of S. tiliifolia and the leaf tannin content of S. splendens were significantly higher under high-fertilization treatment. The soluble protein content of S. splendens and the content of three nutrient indexes of S. tiliifolia significantly increased under high-fertilization conditions. With increasing fertilization, the biomass, flower chemical defense, and nutrient content of both plants increased, while physical defense and leaf chemical defense decreased. Under the same conditions,the plant height, number of leaves, number of flowers of S. tiliifolia were higher than that of S. splendens. Additionally, S. tiliifolia had higher leaf chemical defense and physical defense than that of S. splendens, while the flower chemical defense and nutrient content were lower in S. tiliifolia compared to S. splendens. Notably, S. tiliifolia showed higher leaf chemical defense than flower chemical defense, whereas the opposite was observed in S. splendens. [Conclusions]Both plants reduce defensive investment and increase growth and reproduction under conditions of abundant resources. S. tiliifolia focuses on leaf defense, with stronger growth, reproduction, and leaf defense than S. splendens, which focuses on flower defense. The flexible resource allocation strategy of S. tiliifolia is advantageous for successful invasion.