In recent years, XML technology has won wide attention from both industry and academic. It can be used to mark data, define the data type and their own markup language. It is a cross-platform, context-dependent technology in the Internet environment and an effective tool for todays distributed structure information. The S-XML is a new approach for storing semi-structured data, and it supports query of the node in XML with SQL statements, which has shown impressive performance on many classic data sets. However, it is difficult to store XML data into a relational database, and the S-XML spends much more time and space to store the data. In this paper, we propose an efficient mapping approach, the mini-XML, to mapping XML into the relational database. In addition, path technique and position information are used to indicate the complex node relationship. Finally, two experiments are conducted to prove that the proposed method can achieve better performance in the decreasing of the storage time and storage space, especially dealing with the large amount of data.