Using students' assessments of teaching at a top university in China from 2016 to 2021, this study examines whether evaluation of teaching improves teaching quality. Given the many doubts about the validity of students' evaluation of teaching, this study adopts a methodology to distinguish teaching quality improvement from the reversal effect. It shows that instructors with a poor (good) ranking in the previous evaluation are more likely to receive an improved (decreased) ranking in the current evaluation. This reversal effect is more pronounced among the instructors who are associate/assistant professors, younger and female. This study provides evidence that supports the reversal effect rather than the improvement.