Abstract: To investigate the factors and methods to extract clear configuration in the topological optimization of continuum structure, a topological optimization model using nodal density as the design variable is established. Checkerboard patterns are naturally avoided based on the continuous density field. Combined with density filtering technique to improve the smoothness of density field, the mesh-dependence phenomenon is overcome. Solid isotropic microstructures with penalization (SIMP) density-stiffness interpolation and a modified two-step filtering scheme suggested not only to eliminate the image diffuse phenomena, but also to decrease the number of nodes composed of gray level images. Density contours are adopted to interpret the topological optimization result and continuous contour thus obtained. The validity of the proposed methods are substantiated by some typical two-dimensional examples.