Rough relational database model provided a processing method for uncertainty data, So based on the Hash technology and the data characteristic of rough relational database, it was researched the multiple value data item in the rough relational database represented by binary string in virtue of equivalence classes, calculated its decimal value, and constructed Hash Function. Then according to the decimal number distributed Hash address where stored the data of the rough relational databases. Finally, an algorithm for constructed method of Hash function for the rough relational databases was described and illustrated by an example,and proved the method is validity and practicability.