The cold recovery factor of extra-heavy oil reservoirs with foamy oil flow characteristics is lower than 12%. Conventional steam injection thermal processes are unsuitable as post-cold EOR candidates due to high investment and heavy carbon emission. Meanwhile, the viscosity of foamy oil would increase sharply after pressure depletion and degassing, making it is difficult to achieve a favorable oil displacement effect with non-thermal recovery technologies. In view of this, an innovative technical approach of injecting viscosity reducer slug plus hot water foam slug to improve the recovery of foamy oil reservoirs, called Hybrid Recovery Process by Moderate Heating here, was proposed in this study, and laboratory tests such as formula system screening were conducted. Waring Blender stirring method was used to evaluate the foaming performance of different types of foaming agents, and foaming agent concentration and temperature sensitivity evaluation experiments were carried out to select the foaming agent. The viscosity reduction performance of viscosity reducers at different temperatures was evaluated to select the optimal viscosity reducer. Injected gas type and the injection mode of the composite agents were optimized through one-dimensional core displacement experiments. Through above indoor experiments, a modified AOS-1 foaming agent with a temperature resistance of 150 ℃ and a concentration of 0.5wt% was selected as the foaming medium for the hybrid recovery process. The selected optimal injected formula system includes naphtha as viscosity reducer, hot water, AOS-1 foaming agent, and methane gas. Prepositioned naphtha slug was injected firstly, followed by alternating injection of the hot water foaming-agent solution slug and methane gas slug. In this way, the hybrid fluid is easy to be injected; and foam would form in situ through shear mechanism, which helps maintain formation pressure. And an oil displacement efficiency up to 40% can be achieved, which is far greater than that of cold production and pure hot water flooding. This study provides a novel alternative green and low-carbon post-cold EOR approach for foamy oil reservoirs.