Abstract: Static experiments were carried out to validate the performance of a compound scale inhibitor, that is composed of the polyepoxysuccinic acid (PESA), polyaspartic acid (PASP) and acrylic-2-acrylamide-2-methylpropane sulfonic acid copolymer (AA/AMPS). Its scale inhibiting mechanism was discussed with SEM. The experimental results showed that the compound scale inhibitor has favorable properties of scale inhibition for CaCO3, CaSO4 and Fe2O3 in comparison with the imported scale inhibitors such as MDC220 and PTP-0100. The effects of hardness and alkalinity of water on the scale inhibition rates of the compound scale inhibitor are comparatively low. SEM images of CaCO3 and CaSO4 crystals indicated that the inhibitor causes the crystal lattice of scale to be distorted, then the regularly dense crystal structure transforms into amorphous state.