Shortly after the advent of lasers, researchers began to use coherent beam combination techniques to achieve high energy output of laser systems. Passive coherent combination technology have the characteristics of simple structure, expandablility and the ability to realize phase locking between single lasers by using the self-organization of the system, so it has attracted much attention in the field of high-energy laser. Passive coherent beam combination schemes based on all-fiber structure, multi-core fiber structure, self-image external-cavity structure and ring cavity structure and the related research progress are introduced, and the advantages and disadvantages of these schemes are summarized. In coherent beam combination technology, coherent efficiency and brightness are two important parameters to evaluate the coherent combination effect.