Abstract: This article introduces a remediation case of petroleum hydrocarbon pollution in a typical machinery factory of the Yangtze River Delta region, and expounds the process of in-situ electrical resistance heating technology during remediation of organic pollutants in groundwater. The groundwater and soil were warmed simultaneously to approximately 100 ℃ by the heat that resistance generated in electric field, and the pollutants were desorbed from groundwater and soil and extracted through multi-phase extraction wells, which were treated subsequently on the ground. Amounts of underground temperature and pressure monitoring wells were set to reveal remediation process, and some groundwater monitoring wells were also built to collect groundwater samples regularly and evaluate remediation efficiency. Results of contaminants concentration in groundwater showed that after 50 days of in-situ heating (so-called interim period of remediation) petroleum hydrocarbon concentrations of 65% samples collected in the monitoring wells were below the remediation target value, and after 108 days (last period of remediation) the number reached 100%. In the later stage, further tracking and monitoring of petroleum hydrocarbon concentration in groundwater is needed to verify long-term remediation efficiency of the technology and provide credible data and successful experience for its subsequent application.