Amphoteric water-coal-slurry dispersing agent and preparation method thereof

The invention provides an amphoteric water-coal-slurry dispersing agent and a preparation method thereof. The method comprises that: after polyethyleneglycol and polymerization inhibitor hydroquinone are mixed, acrylic acid, catalyst paratoluenesulfonic acid and a water-carrying agent dimethylbenzene are sequentially added to the mixture, are heated to react and are decompressed and distilled to obtain pale brown transparent liquid; the pale brown transparent liquid is adjusted to neutrality by Na2CO3 solution, is washed by saturated NaCl solution, and is extracted by 30ml aether to obtain anintermediate product I; deionized water, sulphonate or sulfoacid, cationic monomer and sodium bisulfate are stirred and dissolved; and the intermediate product I is dripped into persulfate aqueous solution to react to obtain polymer solution of an amphoteric ionic dispersing agent. The amphoteric water-coal-slurry dispersing agent synthesized by the preparation method introduces a long-chain groupon the premise that the a