Self-organization is a universe mechanism in nature. In a self-organizing system, the system evolves spontaneously to form an order structure based on some compatible rules. Without external instructions and forces, the self-organizing system arises only from the interactions between the basic components of the system. Although numerous theories and methods were established to describe self-organization, there are still many problems in this area. We still lack of unified theories and thoughts on self-organization. Also, we lack of universal basis of methodology in the modeling and simulation of self-organization. Self-organization is classified into a research area in complexity science. So far it is not an independent science. For this reason, a fundamental science, selforganizology, is proposed for finding and creating theories and methods from self-organization phenomena in nature, simulating and reconstructing self-organization phenomena, exploring mechanisms behind numerous self-organization phenomena, and promoting the applications of self-organization theories methods in science and industry. Existing theories and methods of self-organization are overviewed. Methodological basis of selforganizology is shortly discussed.