When evidences combine and fusion, because the unknown new propositions appear in system and the sensor gathered evidences are uncertain, the D-S combination rules are inapplicable for conflict evidence combination. In order to manage the conflict evidence effectively, a modified conflict evidence reasoning method based on non-closed frame of discernment is proposed. First, an aggregate denoting unknown new proposition is added in closed frame of discernment, then the closed frame of discernment is expanded to non-closed frame of discernment, and the evaluate method of new proposition basic probability assignment is given, the focal element combination method in non-closed frame of discernment is given based on the relations between the new proposition and the known evidence. With this as the foundation, the local conflicts are distributed, on the basis of the basic probability assignment and the reliability of evidence among the conflict focal elements. Finally the distribution method of conflicts is verified through an example. The result shows that this proposed approach, compared with the result of with Dempster combination rules in non-closed frame of discernment, is effective in identifying the new propositions. By the modified evidence reasoning method and closed frame of discernment, two kinds of conflicts of new proposition between known evidences and between known evidences can be distributed locally by non-closed frame. By managing the two reasons of conflict evidence in a comprehensive way, the final evidence reasoning result focus on the reasonable direction.