As a search engine is a kind of data-intensive application,its performance is greatly affected by the underlying distributed file system. This paper deals with the performance evaluation and optimization of the distributed file system oriented to search engine application. In the investigation,first,the factors affecting the performance of distributed file system and the relevant research progress are summarized. Then,an open architecture based on Hadoop is designed to systematically evaluate the performance of HDFS and Lustre in search engine scenarios. Finally,several improved schemes are proposed to overcome the shortcomings of HDFS in terms of write performance and small file disposition clarified by the results of performance assessment,which provides a reference for the optimization of distributed file system.