The invention discloses a rotary turbulent-flow fertilizer continuous liquid mixing device for water conservancy irrigation. The device comprises a liquid outlet hopper, a liquid filter screen, a liquid collection hopper, a second hydrocyclone, a first hydrocyclone, a motor, a rotation shaft and a feed liquid mixing tank body, wherein the bottom end of the feed liquid mixing tank body is fixed ona bracket; the liquid collection hopper is welded at the bottom of the feed liquid mixing tank body; a first screen frame and a second screen frame are fixed in the feed liquid mixing tank body; the first screen frame is arranged above the second screen frame; a first screen is mounted in the first screen frame; a second screen is mounted in the second screen frame; fertilizer is dissolved and mixed through double stirring of the first hydrocyclone and the second hydrocyclone; under the filtration and friction in the first hydrocyclone and the second hydrocyclone, the up-down turbulent flow movement, formed by the cooperation between the fertilizer dissolution and the rotation of an external swirl vane, promotes further dissolution; thus, the fertilization dissolution is accelerated, and sufficient dissolution is improved; the problems of slow fertilizing mixing, insufficient mixing and direct discharge of fertilizer particles that are not completely dissolved are effectively solved.