Abstract: The catalytic reduction of CO2 to CH4 serves as a critical pathway for carbon recycling and renewable electricity storage, possessing dual strategic values of environmental emission reduction and energy reserve. This review systematically sorts out the research advances of five technical routes including thermocatalysis, electrocatalysis, photocatalysis, plasma catalysis and multi-field coupled catalysis, with emphatic discussions on reaction mechanisms, catalyst design strategies, reactor engineering and system integration. The advantages, bottlenecks and technological maturity of each technical pathway are comparatively analyzed. Thermocatalytic CO2 methanation is the technology closest to industrial application at present. Ni-based catalysts can achieve high conversion efficiency and CH4 selectivity above 95% under industrial operating conditions of 300-400 °C. Nevertheless, this technology suffers from high energy consumption at elevated temperatures, and it is difficult to balance low-temperature activity with long-term stability. The energy barrier for the rate-determining step of *CO hydrogenation is synergistically regulated by the d-band center and surface hydrogen coverage. This technical route encounters engineering obstacles such as limited heat transfer, local hotspots and catalyst sintering in industrial fixed-bed reactors, which urgently requires the construction of a three-dimensional evaluation system covering activity, stability and impurity resistance. Electrocatalysis operates under ambient temperature and atmospheric pressure. Cu-based catalysts deliver a CH4 Faradaic efficiency of 60%–80% in H-type electrolytic cells. However, restricted by mass transfer limitations and competitive hydrogen evolution reaction under industrial-grade current densities, the selectivity drops sharply to below 30%. In addition, its current manufacturing cost is far higher than the market price of natural gas, leaving a substantial gap to the threshold of economic viability. The core challenge lies in the coordinated optimization of high current density, high selectivity and long-term operational stability. Photocatalysis directly harnesses solar energy, and remarkable progress has been made in selectivity regulation for TiO2-based and MOF-based systems. Unfortunately, the apparent quantum efficiency is generally lower than 1% and the solar-to-fuel efficiency is less than 0.1%, which is more than two orders of magnitude away from industrialization targets. The fundamental restricting factor is that the recombination rate of photogenerated carriers far exceeds the surface reaction rate. Large-scale scaling-up faces engineering bottlenecks including uneven light field distribution and limited mass transfer at gas-solid-liquid three-phase interfaces. Plasma catalysis enables CO2 activation under low temperature and atmospheric pressure, yet its energy efficiency is usually below 10%, with most electric energy dissipated in non-reactive pathways. Photothermal synergistic catalysis combines localized surface plasmon resonance effect with photothermal conversion, realizing high CH4 selectivity at temperatures markedly lower than those required for conventional thermocatalysis. Systems such as Ni/CeO2 and Ru/TiO2 have demonstrated promising potential for enhanced photothermal synergy. Photoelectrocatalysis integrates photoelectrodes with external bias voltage to reduce reaction overpotential and modulate product distribution simultaneously. On the basis of the above analysis, this review proposes that the future development of each technical route should follow differentiated orientations: thermocatalysis shall shift from pursuing “high activity at low temperature” to industrial adaptation featured by “wide temperature range and strong impurity resistance”; electrocatalysis shall take “high energy efficiency and long-term stability” as core objectives to promote stable operation of membrane electrode assemblies for thousands of hours under industrial-level current densities; photocatalysis needs to break through the limitations of material modification and turn to tackling key problems in photoreactor engineering and system integration; multi-field coupled catalysis shall evolve from discovering qualitative synergistic phenomena to revealing quantitative mechanisms and optimizing energy matching. The combination of in-situ dynamic characterization techniques, machine learning-accelerated rational catalyst design, and the establishment of a full-life-cycle techno-economic assessment system will collectively drive the industrialization of CO2 methanation technology toward high efficiency, long-term stability and economic feasibility.