As the large-scale data on molecular interaction available increases, the study on biological networks has ignited more and more attention. As the execution level of cellular functions, the structural composition of metabolic networks not only reflects the execution of cellular functions step by step, but also influences the pathway analysis of metabolic engineering. Hence, as a key step, a sound decomposition of global metabolic networks is not only significant for further exploring the structure and function of genome-scale biological networks, but also necessary for favorably developing the pathway analysis of metabolic engineering. Having reviewed the fruitful study of the macro-structure and topological characteristics, and analyzed some available decomposition approaches, this paper concludes that the lack of reasonable and purposeful evaluation criterions is one urgent problem in the present study of metabolic network decomposition. Besides, the future trend is to develop more effective decomposition models with more information and by more advanced approaches, as well as expanding the application range of network decomposition.