Abstract: Permutation analysis is proposed to describe the braiding process of 3-D preform with rectangle cross-sections.One example of the application of the proposed method is presented firstly.When a braiding cycle is expressed as a product of disjoint permutation,the relationship between the disjoint permutations and the movement of bobbins is developed.The process of 3-D preform braiding with □-shape cross-section is analyzed as another example to describe the application of the proposed method to braid profiled preforms.Based on the expression of the product of disjoint permutation,the types of braiding bobbins can be discriminated and their initial positions be determined,apart from the deduction of the relationship between the disjoint permutation and the movement of bobbins, thus laying a foundation for braiding a profiled preform.