The invention provides a water body treatment construction and maintenance method and an artificial lake. The water body treatment construction and maintenance method is simple in process and environment-friendly; the use of white alum, copper sulfate and the like for purifying water can be completely abandoned through a biological self-purification effect in combination with a combined action of submerged plants, microorganisms and ecological balance control; and the water does not need to be changed, so that the water cost can be greatly reduced and a water body can be ensured to be crystal clear all year round. The water body treatment construction and maintenance method is especially suitable for vast areas in south of the Yellow River. The artificial lake has an excellent ecological self-purification function, and is simple in construction and maintenance method and high in water quality.