The robustness of complex biological networks means that networks are in a position to maintain their functions despite external and internal perturbations. It is a key characteristic of biological networks and might play an important role in the evolutionary process of biological networks. The purpose of this paper is, by investigating the fundamental organizational principles such as the so-called "bow tie" structure, "scale-free" structure and modularity that underlie B. thuringiensis metabolic network, to analyze some simple robustness mechanisms of B. thuringiensis metabolic network with their underlying significance. Furthermore, the analyzing of robustness of well-known citric acid cycle in two typical bacteria is used to illustrate the underlying usefulness of robustness in biological networks.