When inertial friction welding of Al/Steel rod, the welding interface temperature is a crucial factor affecting the welding quality, but the welding temperature cannot be directly controlled, so the energy input in the welding process can only be controlled by controlling the welding parameters, and then controlling the temperature of the welding interface. Temperature field analysis is particularly important for analyzing the influence of welding parameters (speed, inertia and top forging pressure) on the welding quality. The value of the highest temperature and the duration of the maximum temperature play a decisive role in the type and quantity of compounds generated at the Al/Stl rod welding interface. The longer the high temperature lasts, the more compounds are generated at the welding interface during the welding process. To improve the welding quality, the generation of compounds must be controlled. In this paper, a suitable temperature acquisition system is established to collect the temperature of the steel rod characteristic points during the Al/Stl rod inertial friction welding. For welding of 70 mm diameter, the welding process lasts 2–3 s. Because the welding process lasts for a very short time, the temperature acquisition system is required to be sensitive, low delay and high sampling rate. Due to the different temperatures in different areas of the welding interface, it is necessary to compare the temperature in different areas of the interface, and the temperature of multiple characteristic points of steel rods should be monitored simultaneously during the welding process.