TFS series electronic thermal flow switch is developed based on the thermal principle. The closed probe contains two resistors, one is heated as the sensing resistor and the other is not heated as the base quasi-resistance. When medium flows, the heat on the heated resistor is taken away, and the resistance value is changed. Two resistance differences are used as a basis for determining the flow rate. The probe is antifouling coating and can be effective, it prevents the dirt, rust and other dirt in the pipeline from adhering, has stronger anti-pollution ability and is more stable in work.