In this study, a CeO2-loaded In2O3 hollow sphere gas sensor for Diethyl carbonate(DEC) gas detection was designed to predict the thermal runaway of Li-ion batteries. First, pure In2O3 and CeO2-loaded In2O3 hollow spheres were synthesized by hydrothermal method. Then, the interaction mechanism between the material and DEC gas was proposed. Next, a DEC gas sensing unit was fabricated to test its gas sensing performance. In the atmosphere of 100 ppm DEC gas, it is concluded that the best working temperature of this sensor is 200 ℃, and the 2 at% CeO2-In2O3 sample has the largest response, which is about 5.2. The responses of all six samples increased with increasing gas concentration. The 2 at% CeO2-In2O3 sample had a response of 1.01 to 0.1 ppm DEC gas. The sensor also exhibits a short response-recovery time and long-term stability. This sensor holds great promise in predicting thermal runaway of Li-ion batteries.