Abstract: This invention, is a multi-function closet stool, which can really serve the purpose of automatic timing, measuring pressure, flushing and saving water. When one sits on the seat of closet stool, the driving piece pulls the driving steel cable to make timing and piston assembly simultaneously actuate and control arm sandwich on top of a movable piece in the sleeve. When one discharges his urine and stands up, the rear part of seat of closet stool will rebound promptly by the spring; meanwhile, the timing unit begins to count time, then, the driving arm makes the control arm release the movable piece in the sleeve by means of the pulling of timing unit and move upwards by the elasticity of spring. A rubber ring compresses air in the sleeve, the high velocity air will instantly rush in air container through a hole passage, pipe joint, filter and pipe. The air will open a movable lid for the purpose of water-flushing.