The Third United Nations Conference on the Law of the Sea (UNCLOS III) might be the largest and longest international law codification conference thus far. Some scholars attribute the success of this conference to the “package deal” or “great power politics.” This paper adopts the view of constructivism and cites relevant discussions in the field of sociology and replaces Wendt’s “shared ideas” with “meaning framework” for proposing a new analysis framework with operational indicators for international conference decision making. In this analysis structure, the meaning framework and the actor’s behavior are mutually causal in a dynamic construction relationship, while the “shared expectations” are the intermediary of the two. If the shared expectations are met, the two will tend to be stable; if not, they will encounter adjustments. Using the official documents of the “1930 Conference on the Progressive Codification of International Law” to the “1982 Third United Nations Conference on the Law of the Sea,” this article summarizes some observable indicators, such as state claims, text content, rules of procedure, and proposal distinctions, and argues that if the content of the proposal can match current meaning framework produced by state claims and documental textcontent, while also matches the rules of procedure to limited proposals, then the possibility of decision making at international conferences can rise.