Over the past decades, increasingly more critical thinking (CT) in Western countries. attention has been paid to cultivating learners' Chinese educators and teachers have also realized the necessity of developing Chinese students' ability for critical thinking and advocated pedagogical reform. However, the practice of formal instruction in developing learners' critical thinking and related empirical studies are rarely seen. This pilot research, selecting four major critical thinking skills, is aimed to study the effects of formal instruction on the development of Chinese college students' critical thinking ability. With the quantitative and qualitative research, the findings indicate that the intensive instruction is effective in improving the sample's critical thinking ability, NOT in terms of the observed behavioral change, BUT in terms of their unobservable mental awareness.