Abstract: Gas thermal remediation technology (GTR) is an efficient technology to clean up organic contaminants from soil. A case study using GTR in a decommissioned oil-to-gas facility site was introduced. The changes of remediation target temperature, and concentrations of contaminants (COC) in soil, waste water and waste gas with the heating time of in-situ GTR were discussed. The results showed that the temperature of different soil layers finally reached or approached the target temperature at the end of thermal remediation. The COC in soil in the same or similar target areas was at a low level at different time periods and temperatures, and the removal rate reached above 96%. The removal rate of contaminants in waste water and waste gas reached 98.5%-99.8% and the above treatment processes were highly effective. The case study had proved that in-situ GTR could be applied on a large scale.