A limited drainage controller with liquid arranged in the middle comprises a liquid storage tank, and the liquid storage tank is connected with a dosage tank. A communicating opening is formed betweenthe liquid storage tank and the dosage tank. A first control valve is mounted in the communicating opening, and a drainage opening is formed below the dosage tank. A second control valve is arrangedin the drainage opening, and when the second control valve is closed, the first control valve is opened, the liquid storage tank communicates with the dosage tank, and liquid in the liquid storage tank flows into the dosage tank. When the second control valve is opened, the first control valve is closed, liquid in the dosage tank is drained out of the drainage opening. The first control valve andthe second control valve form a linkage valve, the linkage valve comprises a pull rod, and a top valve block is arranged on the upper portion of the pull rod. The top valve block is in contact with the bottom of the liquid storage tank, and a bottom valve block is arranged on the lower portion of the pull rod. The bottom valve block is in contact with the lower face of the bottom of the dosage tank, and toilet cleaner is placed in the liquid storage tank. The storage tank communicates with the dosage tank, and the dosage tank determines the volume according to the liquid dosage requirement. The drained liquid reaches the use effect and is not wasted. By means of valve control, high reliability is achieved, and the service life is long.