Pre-arranged water intake construction method

The invention discloses a pre-arranged water intake construction method which comprises the steps that an approach channel is excavated at a constructed diversion tunnel water intake position, and then rock bodies around a water intake are processed; then a horizontal tunnel is excavated, and lining is carried out; and a concrete plug body is prearranged at a tunnel inlet to block the tunnel inlet, and accordingly early preparation is made for a future-planned diversion project. According to the method, the rock bodies around the water intake are processed before a rock plug body is prearranged and are in a stable state, during rock plug explosion, the danger of landslide caving cannot happen generally, safety is good, the construction period of a later-period diversion project is shortened, investment is saved, and implementation of rock plug explosion can be carried out easily.