Although trilateral cooperation started late，progress is rapid，and in recent years trilateral cooperation has exposed problems on volatility and foundation instability. In view of the trilateral cooperation’s significance and influence，it is necessary to carry out the deeper problems of the trilateral cooperation，especially several important relations. On the basis of comprehensive analysis about five relations such as economic mutual benefit and political mutual trust，intrinsic motivation and external pressure，tripartite cooperation and bilateral relations，the association of ASEAN and north-south imbalance，self-interest and common responsibility，this article has offered corresponding countermeasures and suggestions.