Elucidating the combined exposure of agrochemicals is essential for safeguarding human health and agroecosystem safety. A rapid and high-sensitivity UHPLC-MS/MS method was developed for simultaneous quantification of nine compounds in sorghum by an assembly-line optimization process with a limit of quantitation of 0.001 mg/kg. The concentration variation of atrazine, quinclorac, fluroxypyr-meptyl and metabolites was reflected by terminal magnitudes of ≤0.0665 mg/kg. Additionally, atrazine was dealkylated to deethyl atrazine and desethyl desisopropyl atrazine at concentrations of 0.0014-0.0058 mg/kg during the sorghum harvest. Acceptable health hazardous of atrazine and quinclorac for all life cycle populations were comparatively assessed via deterministic and probabilistic models, in which atrazine gained an 83.55 % share of cumulative dietary risks. Rural residents had significantly higher risks than urban residents, and children were the most sensitive group. Despite the low health risks, combined exposure to herbicides and their metabolites should be continuously stressed, given their cumulative amplification effects.