Abstract: The design of garment pattern CAD relates to many modification methods,one of which is free curve modification.However,many modification modules in the present CAD software have drawbacks.Taken into consideration the practical needs in the curve modification of the garment pattern CAD,a new model value point modification method was proposed. This method was based on thrice uniformity B sample strip constitution,the shape of curve can be changed swiftly with moving of the mouse.It is visual,accords with the habits of designers.It can be applied to modification of part of a curve with no need for recalculating the whole curve.Therefore,this method has the advantages of good controllability,high flexibility,and easy operation.