Aiming　at　the　bottleneck　of　thermodynamics,　kinetics　and　reaction　systems　in　photothermal　catalytic　CO2　reduction　conversion,　a　three-field　coupling　method　based　on　the　efficient　utilization　of　solar　energy　and　the　application　of　a　photo-thermal-magnetic　three-field　was　proposed　to　achieve　efficient　and　highly　selective　CO2　conversion.　The　composite　monolithic　catalyst　with　three　field　response　functions　and　multiple　active　reaction　interfaces　was　prepared　by　using　photoactive　copper　supported　by　nickel　foam.　The　effect　of　an　external　alternating　magnetic　field　on　photocatalytic　CO2　reduction　was　studied　using　a　range　between　0.005　and　0.1　wt%　Cu/Cu2O/Ni(OH)(2)/NF　as　catalysts.　The　results　showed　that　0.01　wt%　Cu/Cu2O/Ni(OH)(2)/NF　exhibited　the　best　catalytic　activity　and　CH4　selectivity　under　alternating　magnetic　field　enhanced　photocatalysis.　The　main　products　were　CO　(6.76　mu　mol　g(-1))　and　CH4　(167　mu　mol　g(-1)).　The　selectivity　of　CH4　was　96.1%.　The　yields　of　CH4　using　this　method　were　11　and　6　times　higher　than　the　yields　obtained　with　photocatalysis　(14.58　mu　mol　g(-1))　and　magnetic-thermal　catalysis　(26.75　mu　mol　g(-1)),　respectively.　According　to　the　analysis　of　temperature　measurements　and　electrochemical　measurements,　the　surface　temperature　of　the　three-field　coupled　catalyst　reaches　about　230　degrees　C.　Applying　an　alternating　magnetic　field　can　effectively　reduce　the　recombination　of　photogenerated　electron　holes.　Alternating　magnetic　field　enhanced　photocatalytic　CO2　reduction　conversion　provides　a　new　and　promising　method　for　the　efficient　conversion　and　utilization　of　solar　energy.