The invention relates to an early-stage rainwater drainage pool capable of self-controlling rainfall at the pool top. The early-stage rainwater drainage pool comprises a rainwater drainage pool body, wherein the rainwater drainage pool body comprises a rainwater inlet runner, a diversion water pool, a rainwater harvesting port and a rainwater drainage control device, and the rainwater inlet runner is communicated with the diversion water pool; a rainwater drainage pipe, a time delay vent pipe and a rainwater harvesting pipe are arranged at the bottom of the diversion pool wall, and a flap valve is arranged at an inlet of the rainwater drainage pipe; the rainwater drainage control device comprises a water harvesting disk, a pulley block, a lever and a water harvesting cylinder, the water harvesting cylinder is movably connected with one end of the lever, and the other end of the lever is connected with the flap valve through the pulley block; and the opening and closing of the flap valve of the rainwater drainage pipe is controlled by the time that the rainwater with set rainfall is harvested by the water harvesting cylinder to separate the early-stage rainwater with high degree of pollution from the middle and last-stage clean rainwater. The early-stage rainwater drainage pool provided by the invention has no mechanical and electrical control mechanism, does not consume energy, does not need manual operation, and has the advantages of simple structure, durability, high reliability, convenience in maintenance and repair and the like.