Systematics is the underlying cornerstone and the oldest discipline of biological science. Due to continuous development of phylogenetic systematics in recent years, incomplete understanding would greatly hinder its further and extensive application. In this paper, we present a detailed introduction of the formulation and development of phylogenetic systematics, and also make a comprehensive comparison of some major approaches to phylogeny. However, the choice of method is still in debate. Therefore, this paper is just devoted to giving Chinese colleagues a relatively complete insight into phylogenetic systematics and encouraging a deeper understanding and application of this theory.