Abstract: A widely used isosurface constructing algorithm is called Marching Cubes which uses small triangles to approximate the isosurface in volume data. There is a problem when applying MC to high density data, i.e: too many triangles are generated to be rendered in real time. The algorithm named Marching Boxes, which is presented in this article, treats this problem by adaptively combining small triangles into larger ones when possible. A precision parameter is used to determine the possibility of combining triangles. The algorithm gives a promising result which half cuts the original amount of triangles with no obvious distortion.