In distributed parameter contact algorithm on three-dimensional contact surface,a method for smoothing three-dimensional contact surface is developed. In the method,a smooth contact surface is interpolated with bi-cubic parametric patches. A bi-cubic parametric patch is defined by using local information such as coordinates and normals of vertexes of patch. The smoothing technique provides an accurate representation of actual contact surface which is C¹ continuous in patches and G¹continuous(tangent plane continuous) between adjacent patches. Then C¹ continuous smooth fields of normal pressure and density on smoothed surface are interpolated. And contact points on smoothed contact surface are calculated with Newton-Raphson iteration. Finally,contact constraints are computed with distributed parameter contact algorithm. Numerical examples demonstrate that smoothed contact surface alleviates‘chatter’of nodes and improves convergence behavior.