Based on the features of ORDM(Object-Relational Data Model) and the query language, a new reference based on join algorithm Sort-Loop is represented. Reference is not only one of the important modeling mechanism, but also beneficial to the design and implementation of joining algorithms, such as Hash-Loops. By overcoming the shortcomings of the Hash-Loops in the data access manner and the use of the main memory, Sort-Loop is of high performance. This is validated by the analysis in the paper.