In this study, we use simultaneous differential scanning calorimetry and thermogravimetric analysis to analyze the solid-state reaction characteristics of Al/Fe2O3 nanothermites before n-Al melts. Different experimental setups for thermal analysis are compared, and the heat-release characteristics are studied on Al/Fe2O3 nanothermites in the form of powder and pellet, respectively. It is found that protection provided by mere argon flow is far from enough for thermal analysis of Al/Fe2O3 nanothermites. The experimental setup must be free of oxygen; otherwise, the determined exothermic peak is mostly the oxidation of n-Al by the residue oxygen molecules in the furnace body, due to the high reactivity and moderate accessibility of free oxygen molecules. Under proper experimental setup, it is found that besides the redox reaction between n-Al and n-Fe2O3, intermetallic reaction also occurs to form Fe4Al13. Moreover, the intermetallic reaction is more noticeable for nanothermite pellet than for nanothermite powder, and the eutectic reaction of Fe4Al13 and n-Al leads to melting peaks below 655 degrees C. The results indicate that instrument configuration and sample status affect the testing results to a large extent, and one should be prudent to derive reaction characteristics of nanothermites.