The invention discloses a long-rubber-barrel high-pressure water injection packer which comprises a rubber barrel and a central pipe, wherein the rubber barrel is sheathed outside the central pipe; the upper end of the rubber barrel is connected with an upper press cap, and the lower end of the rubber barrel is connected with a lower press cap; the upper end of the upper press cap is connected with an upper joint, and the lower end of the lower press cap is connected with a lower joint; the upper joint is internally provided with a pore channel which is internally provided with a multifunctional valve system used for packaging the packer in a sitting way and unpackaging the packer; the upper joint is provided with a decompression hole which is communicated with the upper end of the multifunctional valve system; the inner side end of the packer is provided with a liquid inlet and outlet hole; and the liquid inlet and outlet hole is communicated with the inner side of the multifunctional valve system in a corresponding way.