Abstract: Since the Second World War, economic globalization and regional integration have advanced in parallel. Removing administrative and institutional barriers and deepening regional cooperation have consequently become central concerns of regional research. This paper introduces institutional distance into the study of regional integration and explains its meaning and regulatory mechanisms. Institutional distance has a dual effect: excessive distance raises transaction, management, and adaptation costs, whereas appropriate distance supports complementarity, knowledge exchange, and regional resilience. Effective adjustment therefore requires reducing key institutional distances, integrating regional institutions, selectively increasing or decreasing distance, and maintaining a dynamic yet stable institutional configuration. For China, the priorities are targeted removal of critical institutional barriers, gradual construction of a differentiated institutional pattern, and stronger policy coordination and transmission.