Invasion of alien species threatens the global biodiversity and ecosystem functions. Studying the effects of alien invasive plants on soil physical and chemical properties is helpful to understand the invasion mechanism of alien plants. In this study, the characteristics of soil physical and chemical indexes under different invasion degrees (control, mild invasion, moderate invasion, and heavy invasion) of Chromolaena odorata in karst area of Guangxi were compared and analyzed. The results showed that soil bulk density increased significantly with the invasion of C. odorata. Compared with the control, the soil bulk density increased by 10.3%, 16.7% and 22.3% respectively in light invasion, moderate invasion and heavy invasion habitats, while soil non capillary porosity, total porosity and soil water content decreased significantly, and soil capillary porosity had no significant change. C. odorata invasion had no significant effect onsoil pH value. The contents of soil available P and K increased significantly with the increase of invasion degree. Compared with the control, the contents of soil available P and K increased by 4.3 times and 3.8 times in heavy invasion habitat, respectively. The contents of soil total N and organic matter decreased significantly. The invasion of C. odorata significantly changed the soil physical and chemical properties, resulting in the degradation of soil physical structure and the decline of soil and water conservation capacity of ecosystem in karst area. Meanwhile, the invasion of C. odorata improved the level of soil available nutrients by changing the soil nutrient cycle, created favorable soil environment for itself, and then promoted its growth and spread.