The freeform feature modeling was introduced in HUST-CAID.Classification and parameters were defined combining with the HUST-CAID system(computer aided industry design system developed by Harbin university of science and technology);users could intuitively design any curved surface using a set of suitable parameters provided by the system without concerning the lower layer design.If users want to modify the parameters

the system will correspondingly provide feedback automatically.In order to obtain the right graphics agree with the constraint

it is provided a new novel prototype-driven constraint solving algorithm.The simulation result in HUST-CAID shows that this novel algorithm simplified constraint solving and feature modeling greatly.