The pattern design of brassieres is the core technology for the design and manufacture of brassieres, while the female breast shape and part dimensions are the foundations for pattern design of brassieres. Based upon 3D body scanning, this paper studied the relationship between the breast root shape and the steel ring by considering the features of the pattern design of the brassiere. It concludes that the breast root girth is a complicated three-dimensional curve; it’s inappropriate for the neighboring size’s brassieres to adopt the steel ring with the same specification; the material design of the steel ring should be moderate. The purpose is to provide human body basis for pattern design of brassieres and achieve more standard and scientific pattern design of the brassiere by the underwear enterprises.