Abstract: This paper introduces how to achieve a Jess-based intelligent diagnosis system of local ventilation in the mine field, analyzes how to add rules engine Jess into the development of intelligent diagnosis system, at the same time, it leads the theory of statistics into the inference engine to achieve the reasoning under uncertainty, to reduce the gas explosion in coal mine accident, and to improve the security of ventilation with positive significance.

Key words: diagnosis system, Jess, reasoning under uncertainty, fact base, inference engine