This paper is intended to introduce a new modeling technique for bionic space grid structures. Utilizing the methods derived from bionics and reverse engineering, the modeling technique acquires geometric data points of the natural patterns. Generally, the theory of bionics is used to express the forms of spatial patterns in direct analytic function of curves or surfaces. In this paper, the key point is to express obvious geometric features in data points. For more complicated natural patterns, it is convenient to get data points by three-dimensional (3D) measurement in reverse engineering. So this paper introduces the 3D measurement and explains the manipulations of the data points detailedly. Then the free-form surface of the natural pattern is reconstructed and meshed by the re-interpolation reflection meshing method, which combines the bi-cubic B-spline interpolation of surface and reflection meshing method. In order to satisfy the practical requirement, several meshing ways and evaluation functions of grid quality are proposed. There are several illustrated design examples are presented.