The invention discloses a semi-physical object simulating platform of a power plant instrument control system based on thermal power generation and a control method. The semi-physical object simulating platform comprises a heater, a heat exchanger, an air pump, a turbine and a controller. The outlet of the heater is connected with the inlet of the heat exchanger through a pipeline. A temperature sensor is arranged on the pipeline between the heater and the heat exchanger. The outlet of the heat exchanger is connected with the inlet of the turbine through a pipeline. The outlet of the air pump is connected with the outlet of the heat exchanger through a pipeline. A flow meter and an electromagnetic valve are arranged on the pipeline between the outlet of the heat exchanger and the inlet of the turbine. The controller is connected with the temperature sensor, the flow meter and the electromagnetic valve through an I/O board card respectively. The controller automatically adjusts the flow of air supplied to the turbine and forms feedback so as to more vividly simulate the thermal power generation industrial process.