Research on Systematic Mechanism of "One percent of a thing can result in a hundred-percent error"

One percent of a thing can result in a hundred-percent error." The proposition has been controversial. After analyzing some cases, this paper bring foreword some new concepts based on the theory of eliminating error and system theory, for example the important subsystem, the critical subsystem, the critical chain of subsystems and so on. In addition, the relationship between the error of system and the errors of subsystems or elements has been studied in this paper, and some laws about it have been discovered.