Abstract: Quadratic rotatable combinated design has been extensively used as a method of experimental design at present. Because it is varied in scheme and analysis, it isn't convenient For application. The paper attempts to unify the quadratic rotatable combinated design in aspect of scheme, analysis and computer program on the basis of grasping the substance of the design and understanding the relations among the various types of the design.

Key words: Orthogonality, Regression coefficient, Rotatable design, Combinated design