Abstract: A technique on generation of unstructured grids for three dimensional complex geomtries is presented.Complex configurations are described by several typical kinds of surface patches.A 3D surface patch is first mapped to a 2D segment,then triangulated using a 2D grid generator based on the advancing front method,and finally mapped back to the original 3D shape.Tetrahedral grids are generated by an advancing front method and smoothed by a nodal relaxation technique and a Deluanay transformation.A mesh refinement technique is also given to obtain more accurate solutions.