A serious problem with alien invasive plants always with China and little researches pay close attention to survey and risk assessment of invasive plants in land huge city of our country. Chengdu was set as typical land huge city to survey and create assessment system of invasive plants what was used to analyze the invasive types and assess the risk. In our research，there was more than 80 species of invasive plants in Chengdu，the most family was Compositae，and invasive herb had more than 70 species. As it，there was heavy invasive plant which was difficult to prevent and control in Chengdu，a project for preventing and controlling of invasive plants was needed to protect safety of city ecosystem in Chengdu right now. The main origin areas of invasive plants were tropical and subtropical；the main origin place of invasive plants was America. Warmly and wetly factors of Chengdu provided beneficial environment to invasive plants growth what raised difficulty for control. Serious invasive plants were assessed by the system in our research was the same as our country，there was many serious invasive plants in Chengdu what urgent needed policy，legislation and method to control the problem.