Abstract: The processing precedence relation of the dynamic variations in the concurrent process planning is described with the expansion matrix,which forms the generative process of the matrix with the state transformation and the expansion process with the iterative increment.The main algorithm steps are as follows:1.establishing the constraint set, 2.forming the constraint matrix on the basis of the contraint set, 3.generating the expanded line and column vectors of the precedence matrix, and 4.combining the expanded precedence matrix.Thus,a method with intercrossed concurrent and increasingly iterative perfection for the description of precedence relation in the dynamic CAD design has been worked out.