Abstract: Arbitrary 8-nodes hexahedron elements are used widely and effectively in FEM.In order to realize the volume data visualization of the arbitrarily tessellated hexahedron elements,a new algorithm of iso-surface construction is presented based on the coherence of element nodes.It is easy to determine the position where the iso-surface intersects with the hexahedron elements.And then the iso-line on the arbitrary section can be displayed.This iso-surface-constructing algorithm overrides the restrictions that are imposed by regular cubes.It is simple,useful and reliable.