In nature, the most possible reason that helix is chosen as the basic structure of life molecule is based on its simplest chiral three-dimensional structure. The process of the conversion from chemical molecules to double helical molecules is completed by the topology effect which belongs to the simplest way to form helix, and no external power is needed; moreover, the energy of double helix has fixed drive direction [1]. The dual-branch loop helix (II)—the transition state of double helix has many uses, for example, it can be turned to double helix, and it may be broken into two fragments of a and b which can construct more complicated structures. So the dual- branch loop helix (II) can provide special "building block" of assembling biomembrane and other life molecules.