The invention provides a movable leveling high-precision testing device for a concrete slump extension test. The testing device structurally comprises a frame vehicle, wherein a frame table is configured on the frame vehicle; a support table is arranged at the table top of the frame table; the support table is discoid; the support table is horizontally arranged at the table top of the frame table; a water level is arranged in the center of the support table; a slump extension dial is carved on the table top of the support table; a left lifting rail and a right lifting rail are arranged on the frame table in an extending direction of the diameter of the support table; a fixing rod is horizontally erected between the left lifting rail and the right lifting rail; the center of the fixing rod is fixedly connected with a slump barrel; a controller is connected with a power supply; the power supply is controlled by the controller to drive a track motor, a rotating motor and a vibration motor; a ruler seat is arranged on the frame table; a ruler rack is configured on the ruler seat; a folding length ruler is configured on the ruler rack. A testing process is more normative; a test result is more accurate; the device is more convenient and quicker to move and higher in automaticity.