This paper proposes and argues for an axiom system of information uniqueness, with its core being two formal axioms: `n = n` (Self-Identity of Information) and `n ≠ m` (Mutual Exclusivity of Information). Based on the absolute identity of information content, it strictly defines the concept of "information" as an abstract entity, critically analyzes the essence of "identity confusion" caused by introducing spatiotemporal coordinates or external identifiers, argues that content indistinguishability is the necessary and sufficient condition for information identity, thereby establishing the theoretical foundation for information uniqueness.