In this paper, inhibitor PPGAZMA obtained by the modification of PPG with maleic anhydride (MA) was obtained by the free radical polymerization of acrylic acid (AA) and acrylamide (AM) to obtain the phosphorus-free scale inhibitor AA-AM-PPGAZMA. The synthesized phosphorus-free scale inhibitor was subjected to static calcium sulphate test. Can be AA: PPGAZMA: AM = 4: 3: 1 (molar ratio), the effect of calcium sulfate scale effect of the best, at 3ppm resistance to calcium sulfate scale effect of 96%, also investigated the amount of initiator on the scale inhibitor. The effect of different ion concentration on scale inhibitor was investigated. Calcium sulphate scale was test by scanning electron microscopy (SEM). The scale inhibitor AA-AM-PPGAZMA significantly changed the morphology of calcium sulfate scale. AA-AM-PPGAZMA is a new type of scale inhibitor with industrial application prospect.