Abstract: Interval valued（i-v） fuzzy sets and vague sets are two new theories representing inexact knowledge.They have been widely applied to describe the uncertain data in decision systems.In this paper，the notions and properties of i-v vague sets are first introduced based on vague sets.Then，the score functions of real number vague sets group are extended to i-v vague sets and a new score function is given.Finally，using example to compare all kinds of score functions with the new ones.

Key words: fuzzy sets, vague sets, i-v vague sets, score function

摘要： 区间值（i-v）模糊集合和Vague集是不精确知识表达的两种新理论。他们已被广泛地应用于决策系统中对不确定决策数据的描述。因此在Vague集基础上给出i-v Vague集的相关概念及性质，并将实数型Vague集群决策上的记分函数方法扩展到i-v Vague集上，提出新的记分函数，并用实例比较改进的记分函数与各种记分函数方法的优劣性。

关键词: 模糊集, Vague集, i-v Vague集, 记分函数