In this paper, we describe ideas and related experiments of Tsinghua University IR group in TREC 2004 QA track. In this track, our system consists three components: Question analysis, Information retrieval, and Answer extraction. Question analysis component extracts Query Term and answer type. Information retrieval component retrieves candidate documents from index set based on paragraph level and re-ranks them to find more relevant documents. And then Answer extraction component matches empirical phrases according to answer type to extract final answer.