The invention relates to the technical field of environmental protection, and particularly relates to a water spraying system and a waste gas treatment system. The water spray system comprises a lye tank, a metering pump, a spray water tank, a first water pump, a PH probe, a sprayer device, a tower body and a control device, wherein the lye tank, the metering pump and the spray water tank are sequentially connected; the water outlet of the spray water tank, the first pump, the water inlet of the tower body, the water outlet of the tower body and the water inlet of the spray water tank are communicated sequentially to form a first circulating system; the PH probe is arranged in the first circulating system; the sprayer device is connected with the water inlet of the tower body, and is arranged in the tower body; a smoke inlet of the tower body is formed in the lower side of the sprayer device, and a smoke outlet of the tower body is formed in the upper side of the sprayer device; and the PH probe, the control device and the metering pump are electrically connected sequentially. The water spraying system can be used for automatically adjusting the PH value of the solution in the water spraying system, so that equipment corrosion is reduced, and the service life of the equipment is prolonged.