With the rapid development of Internet, XML is the de facto standard for exchanging and presenting data on the Web. The redundancy of XML data affects XML data transmission, query and other aspects. Data compression is a way to resolve the problem. This paper compares various XML data compression tech- niques, whose cons and pros are compared and analyzed in terms of compression ratio, compression times, and query performance and so on. The survey is concluded by pointing out the future work to be done.