Based on Lukasiewicz's three-valued logic,this paper builds a tri-ary uncertain reasoningmodel,and discusses its some basic properties which shows that it is consistent with our intu-itions. The characters of our model are as follows: 1)its measure for uncertainty is a distribution onthe true-value set of the multi-valued logic, 2)its propagation for uncertainties is related with theoperation of the logic,and 3) its parallel propagation follows a consertative
