Objective To further research the histological composition and characteristics of modiolus by histological observation and three-dimensional recons-truction. Methods Four tissue samples lateral to the angle oris were paraffin imbedded and sectioned, stained with Verhoeff iodine-hematoxylin, observed under the microscope. One tissue sample image among them was put into Winsurf software on personal computer, and then was three-dimensional reconstructed. Results Modiolus in histology was found in orbicularis oris，zygomaticus major muscles，levator anguli oris，depressor anguli oris，platysma pars modiolus and risorius converged in the superficial layer of buccinator lateral to the angle of the mouth. Collagens were thick conspicuously where the muscles converged, and elastic fibers intermixed in it.The thickness of modiolus was 2.52mm, and the apex moduli was ellipse like.Measurements of three-dimensional reconstruction model were carried out. The results were as follows: distance between center point of apex moduli and angle oris was 11.96mm; volume of modiolus was 84.10mmSUP>3/SUP>; perimeter of apex moduli was 27.13mm, area was 18.41mmSUP>2/SUP>；perimeter of base moduli was 33.39mm, area was 28.86mmSUP>2/SUP>. Conclusion Relative to the familiar definition of modiolus in gross anotomy, definition of modiolus in histology which observes under microscope is suggested, also its three-dimensional model is reconstructed, then