As a special subject in the research on information diffusion mechanism in knowledge discovery field, the author presents a new method on deciding to reserve or abandon and understanding the Exception Rule, which is to analyze the changing trend of three parameters(the support, confidence and LS),combining with the analysis of the historical changing trend of the support of the former and latter part of the Rule, in order to receive the acceptable rule and help users to fully understand them, and use them appropriately. This research has a significant effect on the post-disposal of knowledge discovery and its realizability and practicability. As a special subject in the research on information diffusion mechanism in knowledge discovery field, the author presents a new method on deciding to reserve or abandon and understanding the Exception Rule, which is to analyze the changing trend of three parameters (the support, confidence and LS), combining with the analysis of the historical change trend of the support of the former and latter part of the Rule, in order to receive the acceptable rule and help users to fully understand them, and use them appropriately. This research has a significant effect on the post-disposal of knowledge discovery and its realizability and practicability.