中文摘要：

次区域合作诞生于20世纪80年代末、90年代初，在短短20年的发展中，次区域合作研究经历了三次研究方向的转变：第一次是次区域经济合作研究；第二次是次区域经济合作的非经济效应研究；第三次是次区域合作的非经济影响因素及非经济领域合作研究。三次研究方向的转变都有其深刻的背景，体现了次区域合作研究的现实意义和价值。本文对次区域合作的一些基本问题，如次区域合作的定义、特征、分类及其相互影响、理论解释和次区域合作的均衡等进行了探讨。

英文摘要：

Sub-regional cooperation, a new way of cooperation, emerged in East Asia in late 1980s and early 1990s. The paper reviews the previous researches. The authors point out that in the past 20 years, sub-regional cooperative research has experienced three changes in research direction. The first is the researches of the sub-regional economic cooperation which focus on the feasibility and the necessity of sub-regional economic cooperation but not on the sub-regional economic cooperation theory. The second is the researches of non-e- conomic effects of the sub-regional economic cooperation including ＂sub-regional economic cooperation and sustainable development＂, ＂sub-regional economic cooperation and the ecological environment＂ and ＂sub-re- gional economic cooperation and regional social, economic, political＂. The third is the researches of non-eco- nomic factors and non-economic areas of collaboration of the sub-regional cooperation. Non-economic fac- tors include the impact of large countries, border security, non-traditional security and international political pattern. Non-economic cooperation includes security cooperation, environmental cooperation and education cooperation. The changes of research direction reflect practical significance and value of the sub-regional co- operative research. This paper also discusses some basic issues of the sub-regional cooperation including the definition, characteristics, classification and interaction, theoretical explanations of the regional cooperation and the balance of sub-regional cooperation. The authors conclude that sub-regional cooperation can be divid- ed into sub-regional economic cooperation and non-economic cooperation. There are four characteristics of sub-regional cooperation including ＂the content of the sub-regional cooperation＂, ＂openness and complexity of sub-regional cooperation＂, ＂diverse goals and non-compliance of sub-regional cooperation＂ and ＂low-level mechanisms and diversity of sub-regional cooperation＂. Finally, from the