Fractal dimension is proposed to evaluate grit protrusion feature concerning grit protrusion area and length. The aim is to investigate crystal integrate of diamond grit protruded from grinding wheel after dressing. First, 3D crystal diamond grits are established in AutoCAD concerning various crystal configurations. Second, fractal dimension for original diamond grit is analyzed theoretically. Then, dressing experiment is carried out to investigate fractal dimension of grit protrusion topography by suing image processing of SEM photos of dressed grinding wheel surface. Finally, grit protrusion feature is investigated by fractal dimension concerning the depth of cut in dressing process. It is confirmed that fractal dimension can display grit protrusion feature and it may be used to evaluate dressing performance.