The integration of CO2 capture and utilization (ICCU) is an important strategy to realize CO2 emissions reduction and clean energy storage. It has been also recognized as a key negative emission technology (NET) to accelerate the realization of carbon neutrality. Dual function materials (DFMs) with both high CO2 uptakes and excellent catalytic activity are the key to realizing the ICCU scheme. The integrated CO2 capture and in-situ methanation (ICCU-M) process based on Ni/MgO DFMs promoted by alkali metal salt (AMS) has attracted broad attention. The stability of AMS and the reduction of NiO active components are critically important for improving the CO2 adsorption methanation performance of Ni/MgO bifunctional materials modified with molten salts. In this work, NaNO3-promoted Ni/MgO DFMs were prepared and the influence of reduction temperature on ICCU-M performance was investigated. The results indicate that the doped AMS can promote the dissolution and diffusion of CO2 and MgO at low temperatures (～300 ℃), and improve the CO2 adsorption performance. Due to the high temperature (>340 ℃), the dissolution and diffusion of CO2 and MgO are blocked, and the migration of molten salt components covers the active site, resulting in the accumulation and sintering of materials and the decomposition of molten salt, and the attenuation of their adsorption performance. Increasing reduction temperature favors NiO reduction, which can increase CH4 yield, CO2 conversion and CH4 selectivity. After reduction at 450 ℃, the CO2 adsorption capacity and conversion rate of the 10NaNO3-Ni/MgO DFMs (NaNO3 loading of 10%) are 6.46 mmol/g and 79.37%, and the CH4 yield and selectivity are 0.85 mmol/g and 96.27%, respectively. Given the impact of reduction temperature on CO2 capture capacity and methanation activity, a compensatory strategy of catalyst reduction under low temperature and high H2 concentration was put forward, to boost the methanation activity of the DFMs while maintaining the stability of AMS and CO2 adsorption performance.