Given a protein, analyzing the geometric structure of protein is fundamental for the study of a protein folding, docking, interactions between proteins, and so on. One of the important geometric analyses is computing the molecular surface of protein. Discussed in this paper is an efficient algorithm to compute such a molecular surface of protein via the concept of blending operation among atoms constituting the protein. To facilitate the decision for the existence of blending surface among atoms, we take advantage of the proximity information of Euclidean Voronoi diagram of atoms. The proposed algorithm initially detects topological locations where blending surface exist via both edge accessibility and face accessibility of Euclidean Voronoi diagram.