Abstract: In order to develop the application of FAST testing system in the area of testing , evaluating, and predicting wool fabrics’ overfeeding sewing-shrinkage, The theory model was found between the ratio of fabric sewing-shrinkage, the ratio of fabrics’ bending modulus to stretching modulus (modulus ratio of bending and stretching), and fabric overfeeding capacity and other physical items. Based on analyzing the relationship between wool fabrics’ modulus ratio of bending to stretching and the testing items by FAST system, the formula for calculating the modulus ratio of bending to stretching has been established. There is a good leaning relationship between calculating value by using this formula and practical testing value, and this research has extended the application of FAST testing system in the area of optimizing sewing technology design and predicting fabrics’ sewing effect.