Provided is a simulated detecting apparatus for a temperature detector of an oil-draining nitrogen-filling device. A thermal radiation cone is installed over an oil-immersed transformer simulating oil tank. Composite heat-flow meters are installed between the oil-immersed transformer simulating oil tank and the thermal radiation cone, and are connected with a heat-flow and temperature processing system. An oil-draining nitrogen-filling temperature detector is installed on the top of the oil-immersed transformer simulating oil tank. A digital flow velocity meter, an oil temperature detector, and a stirring heating composite device are installed in the oil-immersed transformer simulating oil tank. The digital flow velocity meter and the stirring heating composite device are connected with a flow velocity and stirring comprehensive control system. The oil temperature detector is connected with the heat-flow and temperature processing system. A windbreak is arranged on a side of the simulated detecting apparatus. The simulated detecting apparatus may observe and research temperature distribution cases constructed under different boundary conditions in an omnibearing manner, detects and examines the performance of a temperature detector, and is low experiment table cost, good in repeatability, convenient to operate, and high in accuracy.