Abstract: Database replication technology is an important technology which is aimed at improving the concurrency and fault tolerant of database systems. With replication technology, same data can be stored in distributed system. Because multiple database system provides data access services, database response and concurrency have been greatly improved.This paper is based on the current status of database system applications, analyzes and compares the replication technology of several major databases, such as ORACLE, SQL Server, Sybase and MySQL. This paper focuses on MySQL replication technology and its concrete application in distributed database systems. In addition, this paper also proposed a model of chain replication of MySQL in distributed system. All of these achieve the purpose of data replication in distributed system

Key words: MySQL，Database, Eager replication, Lazy replication, Distributed system