Abstract: Multi-granulation decision rough sets are important model to deal with decision-making under uncertain data and risk from multiple perspectives.In view of the decision-making analysis problem in incomplete information system,this paper firstly introduces the set-pair dominance relation to the multi-granulation decision rough sets,improves the set-pair dominance degree in the set-pair dominance relation,and makes the result more reasonable.Then,the multi-granulation approximation space is expan-ded,and five kinds of multi-granulation decision rough sets models are proposed,which are optimistic,pessimistic,mean,optimistic-pessimistic and pessimistic-optimistic under the set-pair dominance relation.Meanwhile,the related properties and the relation among these models are discussed.Furthermore,combined with the theory ofthree-way decisions,the loss function is represented by interval value in incomplete information system,and different thresholds are obtained.Then five corresponding variable three way decision models are established,and the decision rules are derived.Finally,the case of employee evaluation shows that the proposed model is more flexible in practical application,not too loose or too strict,and the final decision is more reasonable.It provides a novel method for decision-making of uncertainty problems in incomplete information system.

Key words: Incomplete information system, Multi-granulation, Multi-granulation decision rough sets, Set-pair dominance relation, Three-way decisions