A method for simultaneous quantitation of rimsulfuron, quizalofop-P-ethyl and quizalofop-P in potato plant, soil and potato tuber samples was established. The mean recoveries of rimsulfuron, quizalofop-P-ethyl and quizalofop-P in different matrices spiked with them were 81.4%–101.1%, 76.1%–99.0% and 77.4%–106.4% with relative standard deviations (RSDs) of 2.7%–13.3%, 0.9%–5.5%, 1.7%–11.3%, respectively. The open-field trials in China were conducted in potato cultivation system of Changchun and Jinan. The results indicated that the half-lives of rimsulfuron and quizalofop-P-ethyl were 0.04–13.1 days. The residues of quizalofop-P during the harvest time in Jinan soil were < 0.01–0.044 mg kg⁻¹, while there was no residue of target herbicides detected in all other samples. The risk assessment results demonstrated that the risk quotients (RQs) of rimsulfuron and quizalofop-P-ethyl were 7.857 × 10⁻⁵ and 8.730 × 10⁻³, respectively, which exhibited an acceptable dietary risk to Chinese consumers.