In order to deal with the difficulty of ranking interval numbers in the multiple attribute decision making process, interval numbers are expressed in the Rectangular Coordinate System. On the basis of this, two-dimensional relations of interval numbers are analyzed. For interval numbers, their advantage degree functions of the symmetry axis and the length are deduced after an information mining process, and then the advantage degree function of interval numbers is defined. Procedures of ranking interval numbers based on degrees for multiple attribute decision making are given. Finally, the feasibility and the effectiveness of this method are verified through an example.