A ultraviolet-visible spectrometry method of determining insoluble xanthate heavy metal complexes in flotation wastewater was the first time to be put forward. In this work, the changes of ultraviolet-visible spectra of xanthate solution after the addition of various heavy metal ions were investigated firstly. It was found that Pb2+ and Cu2+ can form insoluble complexes with xanthate, while Fe2+, Zn2+ and Mn2+ have little effect on the ultraviolet absorption of xanthate solution. Then the removal efficiencies of filter membrane with different pore sizes were compared, and the 0.22 μm membrane was found to be effective to separate copper xanthate or lead xanthate from the filtrate. Furthermore, the results of the study on the reaction of sodium sulfide and insoluble xanthate heavy metal complexes showed that S2- can release the xanthate ion quantitatively from insoluble complexes to solution. Based on the above research, it was concluded that the amount of insoluble xanthate heavy metal complexes in water samples can be obtained through the increase of free xanthate in the filtrate after the addition of sodium sulfide. Finally, the feasibility of this method was verified by the application to the analysis of flotation wastewater from three ore-dressing plants in the Thirty-six Coves in Chenzhou.