Abstract: Rules credit is determined using rough set approach and consequence credit is determined using fuzzy degree function so as to enhance the reliability of inference because of reasonings comprising subjective influences and non-precision in supportability qualitative indexes evaluation using the weighted fuzzy Petri net.Finally,based on some supportability qualitative indexes of naval gun equipment,credit is validated using matrix operation and calculating of the weighted fuzzy Petri net,and the qualitative indexes are evaluated.The results show that the method is feasible and can not only evaluate the reasoning of integrated logistic support of equipment on duty,but also layout the supportability design of the system at initial argumentation.