The design of fuzzy controller was the key of fuzzy control system, while the core of fuzzy controller design lies in fuzzy rules, whose performance determines the control effect of fuzzy system. General fuzzy rules were obtained from expert experience, in which much subjectivity exists. In this paper, a fuzzy controller was designed and genetic algorithm was improved by taking an intelligent cantilever beam as the research object. A method using the improved genetic algorithm to optimize fuzzy rules was proposed, and the genetic coding as well as the fitness function were confirmed. The simulation model of intelligent cantilever beam was built by Matlab/Simulink, and the vibration control effects of fuzzy controller optimized by GA were compared with those unoptimized. The simulation results indicate that the vibration amplitude of intelligent cantilever beam has a significant decrease and the vibration decay rate has a significant increase after the fuzzy rules is optimized.