Abstract: There is a great deal of causal logic in trouble-shooting programs of conventional hydropower simulation system, in which the relations are so complicated that the programs are difficult to maintain and modify. The Rule Engine technique is thus introduced into trouble-shooting process of hydropower simulation system, i.e. the open source Rule Engine Drools is introduced to rewrite the trouble setting program so as to reduce its logical structure. A series of tests are then conducted to the modules relevant to the trouble-shooting programs in coach and trainee systems. Compared with the 1.0 version of the Fengman hydropower simulation system, the results show that both the executing time and number of trouble codes decrease in the 2.0 version in which the Rule Engine technique has been introduced, and the codes are easier to maintain by professional technical personnel so as to save R and D cost.