The invention discloses a pre-purification hydraulic, automatic and selective water intake device, including a water intake head, a support rack, a concrete anchor pier, a water pipe, a drug feeding pipe, a workbench and an operating room; wherein the water intake head is an integral cylinder, respectively from top to bottom: a balance pontoon, an adjustment water tank, an equipment room and a coagulation basin; two sets of water inlet pipes equipped with waterproof electric valves and water outlet pipes connected with submersible pumps are arranged inside the adjustment water tank, and the drug feeding pipe is arranged in the equipment room; the coagulation basin has a water intake and a water drain pipe, a baffle is arranged in the middle of the coagulation basin, and a coagulant nozzleis arranged above the water intake; the upper end of the support rack is the workbench, the lower end of the support rack is fixed on the bottom of the lake via the concrete anchor pier, and the water intake head can slide on the support rack upward and downward to freely adjust the water intake level; and, the water drain pipe on the water intake head is in turn connected with a metal bellow, a PE water pipe and a fixed water pipe on the bank via flanges. The device is simple in structure and convenient in installation.