Abstract: In the HAc medium, polyacrylamide (PAM) reacts with NaClO to form hydrophobic ammonia chlorate nanoparticles, which have a strong resonance scattering (RS) peak at 480 nm. The RS intensity at 480 nm (I_{480 nm}) increases linearly with the PAM concentration in the range of 1.6～80.0 mg/L, and the detection limit is 0.30 mg/L. The effect of coexistent substances on the determination of PAM has been studied, showing that this RS method has a good selectivity. PAM in synthesized waste water samples was detected with this method with satisfactory results.