Data warehouse provides architecture and tools for business executive to systematically organize, understand and use their data to make strategic decision. On the other hand, XML is used for e-commerce and Internet based application. Since many organizations use web for their business purpose, researches has been done for integrating XML data into data warehouse. This paper illustrates an approach for integrating XML data, modeled by XML schema to its compatible data warehouse based on relational online analytical processing (ROLAP). In this paper, this modeling is performed in three steps. Firstly, a schema tree is constructed from the given XML schema. In the next step, an entity-relationship diagram (ER Diagram) is derived from this schema tree. At the end, dimension tables as well as the corresponding fact table have been identified from the ER Diagram to provide a suitable multidimensional data model for online analytical processing (OLAP). The relationship between the fact tables and dimension tables have been organized in the form of star schema or snowflake schema as required.