Nuclear proliferation is one of the core security issues of the contemporary world,covering both traditional and non-traditional areas. The lack of balance between national security and international security is the fundamental internal drive that has led to the recurrence of nuclear proliferation in the post Cold War time. The paper analyzes the possible inconsistency of interest and legitimacy between national and international security, and proposes interest paradox in proliferation. It has also examined the complex relations between proliferation and international security,and suggested proper prioritization of non-proliferation among all interests involved while recognizing the necessity of cooperation. The continuing existence of nuclear weaponry has its political, security and economic inertia, but it would lose its gound given the push of regional integration and the emergence of a harmonious world.