Interconnected river system network is proposed as a new national water control strategy in the new era, thus study on the connotation and theory of interconnected river system network has become the focus of scientific research. The classification system of riverlake interconnected relationship, various kinds of dynamic “flows” and “the material and energy interchange” and the interactions between rivers and lake were discussed in this paper. And the evolution ways, patterns, the ecological functions of the riverlake interconnected system were also discussed in this paper, etc. Based on these things, the authors had defined clearly the connotation of the riverlake interconnected relationship in this paper. In riverlake interconnected system, the authors considered that there is “the material and energy interchange”, which is the first and foremost material and energy exchange relationship between rivers and lakes. The authors also point out that there are multiple flows between rivers and lakes, viz. material flows (water, dissolved substance, sediment, organisms, contaminants, etc.), energy flows (water level, discharge, velocity, etc.), information flows (information generated with the water flows, organisms and human activities, etc.) and value flows (shipping, power generation, drinking and irrigation, etc.). Under the disturbance of natural and human activities conditions, these flows are based on the connection of rivers and lakes, proceeding “the material and energy interchange” (watersediment exchange, etc.) between rivers and lakes, implementing the riverlake interactions. It is the watersediment exchange of “the material and quantity interchange” between rivers and lakes that is one of the approach and the direct driving forces for evolution of the riverlake interconnected relationship. The river lake interconnected relationship’s evolution tends to relative steady state in the end, which is an ideal dynamic balance. If any changing of whichever elements in river lake interconnected system happened, the others must occur the chain reaction, forming feedback, which affects on the function playing of the whole system, eventually will affect on preventing a flood and fighting a drought, ecological balance, resource utilization and environmental protection in a watershed. We should correctly recognize the river lake interconnected relationship of river network, which has some reference values for the construction of riverlake interconnection project and the water resources department of local government’s decision.