The invention belongs to the technical field of environmental protection, and in particular relates to a device for remediation of organic contaminated soil by using thermal desorption combined with an oxidant and a remediation method. The device of the invention is composed of an air heater, an air compressor, an air valve, a dosing valve, a dosing tank, a vacuum suction pump, a delivery pump, an electric power control unit, an insulation layer, lateral pipes, injection syringes, injection wells, a gas collection well and vacuum suction pipelines. According to the invention, through a treatment method of in situ thermal desorption and adding the oxidant, volatile organic compound contaminated soil is effectively treated. The technique of the invention is applicable to a relatively broad scope, can be used to perform in situ pollution remediation of volatile organic compounds under different climatic conditions, geological conditions, soil properties, and earth surface conditions. The heater of the present invention can infuse more produced heat into the soil, thus saving fuel and combustion time.