Abstract: Power-to-Methane （PtM） technology presents many advantages, including the reduction of CO₂ emissions, the storage of intermittent renewable energy, and the use of existing natural gas infrastructure to address the safety challenges of H₂ transportation. The CO₂ methanation reaction of the PtM process is strongly exothermic, so how to realize the heat coupling between the hydrogen production by electrolysis and the CO₂ methanation reaction has become one of the current research hotspots. In order to assess the impact of different electrolytic hydrogen production technologies on the PtM process and to explore the applicability of different PtM technology routes, a comparative analysis of the energy efficiency and economic viability of coupling High Temperature Electrolysis （HTE） and Low Temperature Electrolysis （LTE） with CO₂ methanation was carried out. The results indicate that under baseline calculation parameters, the energy conversion efficiency of the HTE methanation route is higher than that of the LTE methanation route. Furthermore, after heat recovery, the HTE methanation route achieves an even higher energy conversion efficiency of up to 85.8%. As energy efficiency improves, costs are optimized. Although the cost of the HTE methanation route （9.41 CNY/m³） is higher than that of the LTE methanation （8.91 CNY/m³）, the cost of the HTE methanation route is reduced to 8.23 CNY/m³ after heat recovery, which provides a certain cost advantage over the LTE methanation route. The sensitivity analysis shows that the electricity price is the key factor affecting the production cost. In order to clarify the economic applicability boundary of each technology route, the key point for the impact of electricity price changes on costs was further investigated.The results show that when the electricity price is lower than 0.24 CNY/kWh, the LTE methanation route exhibits a clear cost advantage, while the HTE methanation route with heat recovery demonstrates better economics when the electricity price is higher than 0.24 CNY/kWh. With the continuous improvement of the carbon trading system, carbon reduction technologies such as PtM technologies not only reduce carbon emissions, but also convert environmental benefits into tangible economic gains through carbon market transactions. When the carbon price exceeds 350 CNY/t, the economics of HTE methanation route with heat recovery can be comparable to the coal-based natural gas production.