During this project, I was in charge of query expansion and document expansion with index creation. And I tried to use Wordnet to fetch synonyms and retrieve Web pages’ contents from Google results to expend queries. For document expansion, we did VSM to evaluate similar microblog and retrieved each microblog with 100 similar microblogs. In fact, at first, I came up with an idea about using clustering methods by Mahout API, which although failed finally due to the tense schedule.