Dempster-Shafer evidence theory is a powerful reasoning method in handling uncertain problems. Since Zadeh highlighted the counter-intuitive behaviour of Dempser’s combination rule, a lot of alternative rules have been proposed. However, most of these rules are merely the “patching” of the Dempser’s rule and lack of adequate consideration for evidence compatibility. In this paper, a modified combination rule is proposed based on the concept of evidence ullage. The suggested rule is a general extension of Dempster’s combination rule and aims at solving the counter-intuitive behaviour of evidence theory caused by evidence conflict and evidence compatibility. The parameters of evidence ullage and evidence tendency factor in the modified rule are also discussed and given. Calculated results show that the new rule can resolve the conflict and compatibility problems effectively.