The residual polyacrylamide (PAM) in the treated mineral processing wastewater affects the quality of the return water and its reuse. In this work, a rapid detection method with low detection limit and low concentration of PAM was developed. The ultraviolet absorption spectra of four PAM types with different molecular weights were established in the wavelength range of 190~300 nm. The effects of different concentrations of K+ and Ca2+ on the determination of PAM concentration were studied. The conformation of PAM molecules was analyzed using atomic force microscopy (AFM). Results indicated that the highest absorbance was recorded at 194 nm for four polymers. The detection limit was lower than 0.1 mg.L-1. There was a strong linear relationship between PAM concentration and absorbance (R2 >0.98). With the increase of the concentration of K+ and Ca2+, the intensity of the absorbance characteristic peak of PAM solution gradually decreased. The maximum absorption wavelength continuously redshifted. Moreover, the concentration of K+ and Ca2+ exceeded 50 mmol.L-1 and 5 mmol.L-1, the intensity of the absorbance characteristic peak slowed down. The surface roughness (Rq) of APAM-3 and CPAM-12 deposited on sio2 and Au substrates in deionized water is 24.3 nm and 38.1 nm. When the concentrations of K+ and Ca2+ increased from 10 mmol.L-1 and 1 mmol.L-1 to 100 mmol.L-1 and 10 mmol.L-1, Rq increased from 80.4 nm and 120 nm to 124 nm and 145 nm. Results indicating that the conformation of PAM chains gradually became coiled in solution. The peak value of the absorption peak of ultraviolet spectral features was reduced. At the same time,10 and 100 mmol.L-1 K+ and 1 and 10 mmol.L-1 Ca2+ had the same effect on the conformational change of PAM.