In this paper, we review the complex chemical bond method which has been proposed recently (Wu, Z. J.; Zhang, S.Y. 1999, J. Phys. Chem. A, 103, 4270). The idea of method is that any complex systems with multiple-bond can be decomposed into the sum of binary forms. Thus, if the properties of the obtained binary (real or artificial) system is known, the properties of the multiple-bond systems can then be studied. The method has now applied to many areas such as superconductors, nonlinear crystals, the estimation of lattice energy in inorganic crystals, hardness, etc..