The inhibition behavior of poly(acrylic acid:2-acrylamido-2-methylpropanesulfonic acid:tert-butyl acrylamide) (PAAT) as an environmentally friendly terpolymer on the calcium carbonate scaling in artificial seawater was investigated using electrochemical and chemical screening methods. Therefore, the inhibition mechanism of PAAT was attributed to both threshold and chelating effect. However, the threshold effect had a higher contribution to the inhibition of CaCO3 scaling rather than the chelating effect. The greatest inhibition efficiency of PAAT was achieved at 2 ppm concentration. These results were confirmed by surface analysis methods including scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Moreover, the chronoamperometry test revealed that PAAT has a better inhibition performance than both homopolymer poly(acrylic acid) and copolymer poly(acrylic acid:2-acrylamido-2-methylpropanesulfonic acid).