Abstract: Abstract Dress bust ease is key factor that effects clothing fit . This article analyzed the influence factors and designing method of clothing‘s ease, experimental approach used different thickness underwear, sweater, coat, grouped different wearing level and wearing way by matching each other, measured the same part bust data and thickness of material. Through the experimental data, using stepwise regression analysis method to study the quantity relationship between the chest ease and space and the thickness of coat and underwear under different designing conditions, established mathematical model between clothing bust variation by wearing sweater underwear and thickness of sweater, thickness of underwear. Concluded the linear formula between the bust ease and clothing bust variation by wearing sweater underwear under different fit.

Key words: dress, ease, gap, mathematical model