Abstract: As one of important properties of the textured yarns,the bulkiness was defined as the percentage of the inner space to the whole.It was proved that EIB can do well in testing bulkiness.The bulkiness of air-jet textured yarn could be 70%-75%;and for differential shrinkage and air-jet multi-textured yarn,it is about 5% higher than that of air-jet textured yarn;for combed cotton yarn and worsted yarn,the bulkiness ranges 55%-60%,where the worsted yarn′s was about 5% higher than that of combed cotton yarn′s;the bulkiness of twisted filaments was 20%-30%,of which the value can be increased 2 times when it is textured.