Abstract: In the paper,a modified method for spares demand of military aircraft based on rough sets theory is proposed to the effect of non-quantitative factors on the spares demand of military aircraft.Considering the multi-value properties of non-quantitative factors,original rough sets theory with indiscernibility relation is replaced by the extended rough sets theory with tolerant relation.By approximation space under tolerant relation,the decision rules are acquired,and then the modified coefficients are obtained through the decision rules.Finally,the obtained process of modified coefficients is illuminated by an example of tyre spares.

Key words: spares of military aircraft, demand, rough sets, tolerant relation, modified coefficients