The invention discloses a black-odor urban river wastewater sampling method and device. Firstly, by means of a built-in gas and liquid dual-sampling mechanism, not only can black-odor urban river wastewater be sampled, but also air above a black-odor urban river can be sampled, follow-up detection of the wastewater and the air of the black-odor urban river is facilitated, and a researcher can know whether ambient air of the black-odor urban river is affected by the wastewater; secondly, under the action of an oxygen concentration detection alarm, oxygen content can be detected and alarmed, a worker is prevented from being in an oxygen-deficient environment, and sampling safety of the worker is improved; finally, by means of a lifting mechanism, wastewater in upper layer, middle layer or lower layer of the water area can be specifically sampled as required, and accuracy of detection research is improved. With adoption of the scheme, the researcher can know the contamination status of the black-odor urban river compressively, and follow-up water pollution control is facilitated.