The article focuses on exploring the potential and challenges of tools such as ChatGPT-4.0, Wenxin Yiyan 4.0, and FLYTEK in the teaching of critical writing in university English courses. It examines how to use these generative artificial intelligence tools to guide students in critical writing and provides a detailed analysis of their application in expanding topic content and constructing clear arguments within argumentative essays. The study comprehensively demonstrates the effectiveness of these technologies in enhancing students’ critical thinking abilities and writing quality. Based on experimental results, targeted teaching suggestions are proposed, aiming to provide references for future English writing instruction.