The utility model discloses a layered and integrated water distribution packer of a horizontal well. The packer comprises an upper joint, an upper central tube, a rubber cylinder, a lower joint and the like. The upper joint is sequentially connected with the upper central tube, a central tube, a lower central tube, a lower inner tube and the lower joint. The upper central tube, the central tube and the lower central tube are sequentially connected with an upper stop ring, an upper spring, an upper piston, an upper flushing jacket, an upper stop bowl, the rubber cylinder, a lower steel bowl, a stop jacket, a lower stop ring, a lower spring, a lower piston and a lower flushing jacket. A collar of an upper inner tube is arranged between the upper central tube and an inner tube. A water distribution core is arranged in the inner tube. With the adoption of the packer, the horizontal well realizes the three-layer water injection and allocation, the three-layer allocation is realized only by throwing in the water distribution core and fishing out the water distribution core at one time, and a test instrument is inserted in at one time to test the water absorbing capacity at the three layers at the same time, and the inverse flushing is realized, so that the packer is high in testing and throwing in/fishing out efficiency, low in cost and convenient and fast in operation and is widely applied to the water injection process in oil exploitation.