In order to resolve the long-standing dilemma of abstract interpretations of the principle of universal interconnection in dialectical materialism, this paper takes the microscopic physical mechanism of molecular collisions as a concrete vehicle. After analyzing the three fundamental modes of interaction—elastic collisions, inelastic collisions, and reactive collisions—and integrating deeper operational logics such as mediating coupling, non-linear emergence, and boundary interpenetration, it provides a comprehensive and systematic exposition of the intrinsic characteristics of the universal interconnection of things from three dimensions: ontology, methodology, and praxis. The research reveals that collision interactions at the molecular level are not isolated microphysical phenomena, but rather the microscopic emergent forms of universal interconnection in the material world: the inevitability of collisions confirms the objectivity of interconnection; the diverse modes of collisions correspond to the richness of interconnection; the chain-reaction-like emergence of collisions generates the wholeness of interconnection; and the transformation of mass and energy in collisions embodies the developmental nature of interconnection.