China is one of the countries most severely affected by invasive species. With the increasing number of invasive species, assessing, and classifying invasive species based on their potential damage and impact to strengthen focused management is necessary. In this review, we classified diverse assessment, ranking, classification, and grading methods for invasive species' damage to all species groups, worldwide, and evaluated the advantages and disadvantages of each method. According to the assessment contents and quatification and presentation of the assessment results, the main methods can be divided into four categories: expert qualitative grading and ranking, impact grading and ranking based on literature evidence, grading and classification considering impacts and other factors, and multi-index comprehensive evaluation based on analytic hierarchy process. Among them, two methods, the impact classification for alien taxa and the general impact scoring system, have high repeatability, stability, and scientific evidence and are widely used. We compared these methods in terms of application, assessment objective, content, and results, and method stability and found that the present index systems and Chinese multi-index comprehensive evaluation method used have certain shortcomings, including incomplete evaluation contents and low stability. Finally, we propose improvements for the multi-index comprehensive evaluation method, hoping to improve the Chinese risk assessment method and assessment systems for invasive species. Supporting related research and management work will be needed.