This article utilized the ecology and the diagnostic method viewpoint and the method elaborates the library system ecological equilibrium meaning and the characteristic , analyzed the library system ecological structure coordination , the ecology exchanges the smooth general characteristic , the ecological structure rationality , the ecology function consummation balanced performance , the construction constructs the library system ecological equilibrium pattern 摘要本文运用生态学和辩证法的观点和方法论述了图书馆系统生态平衡的含义和特征，分析了图书馆系统生态环境协调性、生态交流畅通性、生态结构合理性、生态功能完善性的平衡机能，构建了图书馆系统的生态平衡模式。
( 3 ) ecological water requirement of the river system is water demand that maintains and improves the natural ecological structure and function of the river within the definite standard of ecological environment . the composing and the corresponding calculation methods are carried out for ecological water requirement in the southern region ( 3 )针对南方河流的特点，提出了南方地区河流系统生态需水量的概念，指出河流系统的生态需水量是在一定生态环境标准条件下，为了维持和改善河流系统正常的生态结构与功能所必须保障的需水量。
