Abstract: This paper studied the geometric figure of raglan sleeve knit sweater and analyzed the calculating principle of the manufacture technology by using the right-angled triangle of armhole and sleeve top based on the geometric figure and the relation of sizes of front(back)and sleeve pieces.The development procedure of formula including front(back)panel length,front(back)neck opening etc.of raglan sleeve knit sweater is presented in order to build a widely applicable mathematical calculating formula which benefits the accurate calculation of knitting technology of sweaters and can be used as theoretical basis of sweater CAD software design.