In order to analyze the polymerization process of maleic anhydride（MA）and sodium allyl sulfonate（SAS），two variables were designed，such as neutralization degree and initiator dosage，while the formula and process remained basically unchanged. A series of MA/SAS samples were synthesized by changing one of the variables，and then were characterized by nuclear magnetic resonance spectrometer and gel permeation chromatograph. The results showed that the copolymerization activity of MA and SAS was good. When the neutralization degree did not exceed 100%（relative to the mole percentage of MA），a small amount of initiator （2.4 g sodium persulfate） would cause a high monomer conversion，but 6% —8% of the monomers remained unpolymerized. The type and quantity of remaining monomers were closely related to the neutralization degree and initiator dosage. MA was partially hydrolyzed into maleic acid in aqueous solution. Although the amount of maleic acid was relatively small，it could make a bimodal molecular weight distribution of the copolymer as a relatively poor polymerization activity. Adding alkali could neutralize maleic acid. When the neutralization degree did not exceed 100%，maleic acid mainly became a monosodium maleate with good polymerization activity，indirectly promoting the polymerization of MA monomers. When the neutralization degree was 200%，maleic acid mainly turned into disodium maleate，which had relatively poor polymerization activity and seriously hindered polymerization. When it was not neutralized or the neutralization degree was 100%，it took 7.0—7.2 g of initiator to convert all the monomers. At an appropriate neutralization degree（about 20%），a small amount of initiator（4.0—4.2 g）was needed. A more completely polymerized copolymer could be obtained，saving about 40% of the initiator dosage. The static scale inhibition performance of calcium carbonate，calcium phosphate，and calcium sulfate was studied using MA/SAS copolymers synthesized under optimum conditions. The copolymers showed excellent inhibition of calcium phosphate scale and calcium sulfate scale，as well as good inhibition of calcium carbonate scale. The corresponding maximum scale inhibition rates were 94.38%，100.00% and 59.03%，respectively.