Considering the complexity and non-perfection of the stability analysis in fuzzy control systems，we used the view of information theory to study this problem. Based on Lyapunov stability analysis law，the problem is deeply researched and discussed by introducing the concept of information entropy. Through considering comprehensively the dynamic characteristic and stability boundary of fuzzy control systems， the stability definition of fuzzy control systems is given，and a new stability sufficient condition of fuzzy systems is proved by strict mathematical deducing.