In this paper,the definition of mesh control information are given with the topological elements in the B\|reps of the planar domains, node space function is used to control the changes of element size. Integrating the merits of method of advancing front and the Delaunay triangulation algorithm, the longest segment of generation front is preferably dealed with, decreasing Delaunay triangulars are generated step by step and constructing a smooth graded trangular mesh.