Deformable models are of great importance for contour extraction and surface reconstruction, which cause the deformable models deform to the object contours due to simulated external force.Deformable B spline models can share the merit of the popular used B splie. From the Lagrangian mechanics, the dynamics equation of deformable B spline curve and surface is derived. Its finite element solution is studied including the finite element generation and element matrix calculation. A example is given to verify its validity.