《维也纳条约法公约》第31条第3款(c)项为通过条约解释缓解国际法断片化问题提供了依据。但对该条款的适用仍存在许多疑问,其中之一是“当事国”的解释问题。对“当事国”含义的不同解释直接影响到在条约解释时所考虑的相关国际法规则的范围。本文认为,对“当事国”的解释应在遵循条约解释规则和国际法原理的基础上,尽可能的实现维护国际法体系性的政策目标。一种可行的解释范式是,将“当事国”解释为条约当事国,但对“适用于当事国”进行宽松解释,即只要条约当事国通过明示或暗示同意适用相关规则,即可在条约解释中对这些规则加以考虑。 Article 31, paragraph 3 (c), of the Vienna Conventions provides the basis for the treaty interpretation to alleviate the fragmentation of international law. However, there are still many questions about the application of this article. One of them is the question of the interpretation of “the country of the parties”. The different interpretations of the meaning of “the State of the State” have a direct bearing on the scope of the relevant rules of international law that are taken into account in the interpretation of the treaty. This paper argues that the explanation of “party countries ” should follow the rules of treaty interpretation and the principles of international law as much as possible to achieve the systematic policy objectives of maintaining international law. A viable paradigm for interpretation is that “the State of the State” is interpreted as a State Party to the Treaty but that it is loosely interpreted as “applicable to the State”, that is, so long as the State Party to the Treaty applies by express or implied consent These rules can be taken into account in treaty interpretation.