The sulfidization-xanthate method is a commonly used method for recovering smithsonite. The attenuation law of the sulfide layer on the surface of smithsonite was investigated by microflotation test and Local electrochemical impedance spectroscopy (LEIS). The microflotation test showed that the recovery efficiency of smithsonite decreased from 82.58% to 64.16% when the sulfidization time increased from 2 to 10 min. It was indicated that the newly formed sulfide layer is unstable and decays with an extension of sulfidization time. After sulfidization of smithsonite, its surface conductivity is changed. The LEIS method was used to in situ study the conductivity of smithsonite surface. It was revealed that when the sulfidization time was 10-30 min, the electrochemical impedance increased from 7.58 x 10(4) to 7.68 x 10(4) and the conductivity deteriorated. It was indicated that the newly formed sulfide component is unstable and begins to decay. (C) 2020 Elsevier B.V. All rights reserved.