In order to reuse software resources efficiently, developers need necessary quality guarantee on software resources. However, our investigation proved that most software resources on the Internet did not provide enough quality descriptions. In this paper, we propose an approach to help developers judge a software resource's quality based on comments. In our approach, the software resources' comments on the Internet are automatically collected, the sentiment polarity (positive or negative) of a comment is identified and the quality aspects which the comment talks about are extracted. As a result, the merits and drawbacks of software resources are drew out which could help developers judge a software resource's quality in the process of software resource selection and reuse. To evaluate our approach, we applied our method to a group of open source software and the results showed that our method achieved satisfying precision in merits and drawbacks finding.