Abstract: Commenting act is an important category of meta-discourse in academic papers and can be divided into four types: announcing the theme, organizing the text, citing opinions of others and presenting the results. Analysis shows that: 1) Commenting act in German papers is used more frequently than in Chinese, especially in theme announcement and text organization. Chinese authors tend to use more reporting and citing acts; 2) In announcing and organization, German and Chinese papers show the same model of "WHAT+DO", which can be further expanded; 3) In citing and presentation, German authors use more metaphors and deixis than their Chinese counterparts; 4) Generally speaking, German authors use more explicit formulations to communicate with the readers, organize the text and proposition, express their ideas and present the results.