The management of large collections of music data in a multimedia database has received much attention in the past few years. In the most of current works, the researchers extract the features from the music data and develop indices that will help to retrieve the relevant music quickly. Several reports have pointed out that these features of music can be transformed and represented in the forms of music feature strings. However, these approaches lack of scalability while increasing the music data. In this paper, we propose an approach to transform the music data into a numeric forms and develop an index structure base on R-tree for effective retrieval. The experimental results show that our approach outperforms existing string index approaches.