This study aims to identify the aspects of paragraphs that ChatGPT impacts and to explore students' perceptions of this tool. The study used both quantitative and qualitative methods, with 72 fourth-year students majoring in English Language at Thu Dau Mot University participating. The results indicated that ChatGPT had a strong impact on many aspects of the students' paragraphs, including vocabulary, grammar, coherence, organization of ideas, mechanics, and writing style. Students had a positive perception of ChatGPT, considering it a useful tool that saved time, suggested writing styles, and helped improve the structure of their texts. Additionally, feedback from ChatGPT boosted confidence and helped them gain a better understanding of the topics. However, the tool also had some limitations. Concerns were raised about plagiarism, the accuracy of information, and the reduced interaction between teachers and students. Furthermore, excessive reliance on the tool could impact students' critical thinking and creativity, as well as raise concerns about privacy and information security. This study provides practical values for both teachers and students while contributing to the integration of ChatGPT into the learning process to enhance academic performance.