The invention relates to an in-situ rain leaching repair system for contaminated soil. The in-situ rain leaching repair system at least comprises three parts, namely a rain collection part, a leaching repair part and a waste water treatment part, wherein the rain collection part is provided with water guiding pipes, a water collecting tank and canals, the leaching repair part is provided with an observation well, water collecting pipes and plants planted for the soil phytoremediation, the observation well is built in a middle-upper layer of contaminated soil, and the water collecting pipes are in the middle-lower layer; and the waste water treatment part is provided with a filter tank, a microorganism putting tank, an electric separation tank, a wind power generating set and the like, leaching waste water is firstly filtered by the filter tank, and is then repaired by the microorganism putting tank, and finally, the leaching waste water passes through the electric separation tank to process heavy metal so as to obtain the purified liquid. The in-situ rain leaching repair system establishes a complete contaminated soil simulated repairing system for the soil in an aeration zone, and combines repair technologies of leaching, plants, microorganisms, electric separation and the like. The in-situ rain leaching repair system has the characteristics of energy conservation, emission reduction and no secondary pollution, and is suitable for repairing the soil in a large-area aeration zone with little pollution.