Amphoteric polycarboxylate brine coal slurry dispersant with different carboxylic acid monomers were synthesized as allyl alcohol polyoxyethylene ether 500 (APEG-500), carboxylic acid monomers(Acrylic and Itaconic Acid), dimethyl diallyl ammonium chloride (DMDAAC) and other raw materials. FTIR and 1HNMR were used to characterize the dispersant. The dispersant’s dispersion performance and its mechanism of action were tested by the viscosity of coal water slurry, XPS, Zeta potential, contact angle, stability, etc. The results show that when the amount of DMDAAC was 6.0% of the total mass of monomers, the effect of amphoteric polycarboxylate dispersant on reducing the apparent viscosity of coal water slurry was better than that of anionic dispersant; the performance of carboxylic acid monomer as itaconic acid was notable, the maximum solid mass fraction of Yulin coal in Shaanxi reaches 66.53%, the Zeta potential changes from -20.8 mV to -31.9 mV, the thickness of the film and the saturated adsorption capacity were 2.56 nm and 3.23 mg/g respectively, the wettability of the coal particles was better, and the stability of the slurry was significantly improved. Indicating that the dicarboxyl group can improve the performance of the dispersant more than the monocarboxyl group.