A thermal testing apparatuses for a server system (22) includes a heating module (16), at least one temperature sensor (191), a micro control unit (MCU) (192), a trigger controlling circuit (193) and a display module (20). The heating module heats airflow at an entry of the server system. The temperature sensor senses temperature at the entry of the server system, and outputs temperature signals. The MCU receives temperature signals and converts them to temperatures in degrees. The trigger controlling circuit is electrically connected to the MCU to receive a controlling signal, and controls turning the heating module on or off. The display module is electrically connected to the MCU for showing the temperatures in degrees.