This is the third year that we (ICT-CAS team) participated in the Enterprise Track of TREC. The track of this year includes two tasks, being document search task and expert search task. As to the document search task, we compare two retrieval models, namely BM25 model and language model. As to the expert search task, we focus on the authority of persons by exploring the persons' recommendation network constructed from their associated documents. What's more, we investigate the effectiveness of query expansion on both tasks.