The invention discloses a chloro-alkali salt-bearing wastewater treatment system and a method. The system comprises an acetylene generating device, a polymerization device and a caustic soda device, wherein the acetylene generating device communicates with an acetylene supernatant treatment device, and the acetylene supernatant treatment device communicates with a water-mud device; the polymerization device communicates with a polymerized mother liquor biochemical treatment device, the polymerized mother liquor biochemical treatment device communicates with a polymerized mother liquor deep treatment device, the polymerized mother liquor deep treatment device communicates with a production wastewater biochemical treatment device, and the production wastewater biochemical treatment device and a domestic sewage biochemical treatment device communicate with a reclaimed water recycling device; the caustic soda device communicates with a caustic soda wastewater treatment device, and the caustic soda wastewater treatment device communicates with a brine collecting and conveying device. According to the system and the method, in view of wastewater of different types, a wastewater graded utilization mode is optimized, the cyclic utilization of the wastewater is achieved to the maximum, and the discharge of the wastewater is reduced; the utilization ratio of water resources is increasedto the maximum, the production cost is reduced, and finally, the aim of environment protection is achieved.