With the acceleration of industrialization, organic pollutants such as trichloroethylene (TCE) enter contaminated sites through various ways, endangering soil environmental health and ecological safety, and traditional remediation technologies are often difficult to effectively deal with such persistent organic pollutants. In recent years, advanced oxidation process (AOPs) has become one of the potential pollution control methods because of its ability to produce strong oxidizing free radicals. The aim of this study was to investigate the mechanism of the degradation of TCE in soil by the activation of persulfate (PS) by sulfide nano zero-valent iron (S-nZVI). The batch experiment, combined with chemical probe experiment and electron paramagnetic experiment (EPR), showed that when the internal PS concentration of S-NZVI /PS system was 50mmol/L, pH=3, Fe/S=10, and the dosage of activated material was 10mg/g, The degradation rate of TCE in soil by S-nZVI/PS system was more than 85%. Two kinds of free radicals, SO4?- and ?OH, were present in the system, and SO4?- was the dominant active free radical in the reaction. GC-MS was used to speculate that the degradation path of TCE was through electrophilic addition of sulfate radical and finally degradation into ethane. This study shows that S-nZVI/PS system, as a new and efficient soil remediation technology, has broad application prospects in the treatment of TCE pollution, and provides theoretical basis and technical support for further optimization of remediation programs for odor-contaminated sites in the future.