Data replication is a common method used to improve the performance of data access in distributed database systems. In this paper, the authors present an Object Replication Algorithm in Distributed database systems (ORAD). They optimize the created replicated data in distributed database systems by using activity functions of previous algorithms, changing them with new technical ways and applying ORAD algorithm for making decisions. They propose ORAD algorithm with using effective factors and observe its results in several valid situations. Their objective is to propose an optimum method that replies read and write requests with less cost in distributed database systems.