Combining the curve surface deformation technique and the metaball method, a metaball based curve surface constrained deformation model is presented. The field function of metaball expresses the restriction of curve surface deformation that is applied on the surface. Regulation of the parameters of the field function can master the desired deformation result. The parameters include the field function type, the center, the effect radius and the displacement of metaball. Convolution from skeleton achieves smooth surface. Some issues concerning curve surface deformation are discussed in this paper, such as relationship between constraints, the effect of single constraint, to control the influence of other constraint, etc. Several samples illustrate the mechanism and application in the curve surface modeling and soft surface simulating of the model.