ARF is the primary multilateral political and security mechanism in the Asia-Pacific region. Since its inception in 1994，ARF has served as an effective venue for the discussion of political and security issues among countries in the Asia-Pacific. As the result of more and more severe non-traditional security-threaten，acceleration of ASEAN integration process and penetration of the Europe’s Security Co-operation idea，now the second stage of the ARF，the preventive diplomacy （PD） is entering a new development era and presenting new characteristic and new current. In the future the change of preventive diplomacy will affect both ARF’s own development and the process of multilateral security cooperation the Asia-Pacific.