Allyloxy polyethoxy ether (APEG) and succinic anhydride were used to prepare allyloxy polyethoxy carboxylate (APEL). 8-Hydroxy-1,3,6-pyrene trisulfonic acid trisodium salt (PY) was reacted with allyl chloride to produce fluorescent monomer 8-allyloxy-1,3,6-pyrene trisulfonic acid trisodium salt (PA). APEL and PA were copolymerized with maleic anhydride (MA) to synthesize PA tagged no phosphate and nitrogen free CaSO4 inhibitor MA–APEL–PA. Structures of PA, APEG, APEL, and MA–APEL–PA were identified by 1H NMR. The observation shows that the dosage of MA–APEL–PA plays an important role on CaSO4 inhibition. The effect on formation of CaSO4 was investigated with scanning electron microscope (SEM) analysis. Relationship between MA–APEL–PA’s fluorescent intensity and its dosage was studied. Correlation coefficient R2 of MA–APEL–PA fluorescent intensity and MA–APEL–PA dosage is 0.9991.