Based on the current situation of the Lower Yellow River channel, this paper analyses the factors affecting river health, points out that river channel health is the foundation and key to river health. It evaluates the Yellow River's downstream channel health using fuzzy comprehensive evaluation method and gets the conclusion that the Yellow River's downstream channel health has deteriorated in 50 years and has improved in the beginning of this century. This paper analyses and points out that the reservoir to regulate natural flow-sediment process is the primary means that the human impact on river health. The regulation of reservoir has duality that "excessive" regulation will seriously damage river health and "moderate" regulation can better maintain and restore river health. Coordination of flow-sediment relationship is the key to maintaining the health of the Lower Yellow River.