Abstract: Used persulfate-sodium sulfite as the initiator, the synthesis of a quaternary copolymer from 2-acry-lamide-2-methyl propyl sulfonic acid(AMPS), N, N-dimethyl acrylamide (DMAM), fumaric acid (FA), vinyl pyrrolidone (NVP) was studied. By orth-ogonal experimental design, the optimal reaction conditions were obtained as following: reaction temperature of 50℃, initiator amount of 0.12%(wt) and pH7. The product's structure was verified by Fourier transform infrared spectrum (FTIR), hydrogen nuclear magnetic resonance spectrum (1H-NMR), thermogravimetry(TG)analysis, Zeta potentiostatic test and SEM observation, meanwhile found that the decomposition temperature is 320℃ or so. At 180℃, it can control the water loss of cement slurry to 60mL within the API, also discussed the mechanism of reduce water loss of the polymer.