Abstract: The infusion of critical thinking instruction in subject-matter courses has become a focus of research. The objective of this study is to find out whether there are any differences between explicit and implicit teaching methods in the cultivation of students’critical thinking ability by evaluating two 18-week intervention programs aimed at developing critical thinking in writing and evaluation for two classes of fourth-year English majors. The results of the research demonstrate: First， explicit and implicit teaching methods prove to be equally effective in improving students’writing skills in exposition and argumentation. Second， while both methods are effective in the enhancement of students’critical thinking evaluation skills， there is a dramatic discrepancy in the effectiveness of these two methods with the explicit one having an advantage. Third， how to help students make a positive transfer of critical thinking skills to other learning situations and daily life is an area that requires further research.