A method for recycling carbon dioxide from biomass gasification, the method employing only carbon dioxide as a gasifying agent to gasify biomass to yield syngas and employing the syngas to produce oil products in the absence of oxygen, the method comprising: 1) gasification step: employing carbon dioxide as a gasifying agent, allowing the carbon dioxide to gasify biomass in a gasifier in the presence of external auxiliary energy, whereby yielding syngas comprising CO, CO 2, CH 4, H 2, H 2 O, H 2 S, and COS, wherein the gasifying agent carbon dioxide is collected from following steps; 2) cooling step: cooling the syngas using a primary heat exchanger and a secondary heat exchanger in sequence, wherein the primary heat exchanger employs carbon dioxide as a cooling medium whereby preheating the carbon dioxide as the gasifying agent in 1), and the secondary heat exchanger employs water as a cooling medium whereby producing vapor; 3) scrubbing step: introduced cooled syngas in 2) to a cyclone separator and a gas scrubber for dust removal and purification; 4) shift reaction: allowing purified syngas in 3) to react with the vapor so that part of carbon monoxide of the syngas is transformed into hydrogen and carbon dioxide, whereby modifying a ratio of hydrogen to carbon monoxide of the syngas; 5) desulfurizing step: desulfurizing modified syngas to remove H 2 S and COS therein; 6) decarburizing step: decarburizing desulfurized syngas to separate carbon dioxide therein; 7) catalytic synthesis: introducing desulfurized and decarburized syngas to a synthesizing tower where the desulfurized and desulfurized syngas is catalyzed to yield oil products and exhaust gas comprising carbon dioxide; 8) decarburizing of exhaust gas: decarburizing the exhaust gas comprising carbon dioxide and separating the carbon dioxide, and discharging effluent gas free of carbon dioxide; and 9) cycle of gasifying agent: introducing the carbon dioxide separated in 6) and 8) to the primary heat exchanger as the cooling medium in 2) whereby preheating the carbon dioxide, and transporting the preheated carbon dioxide to 1) as the gasifying agent for gasification. 1) gasification step: employing carbon dioxide as a gasifying agent, allowing the carbon dioxide to gasify biomass in a gasifier in the presence of external auxiliary energy, whereby yielding syngas comprising CO, CO 2, CH 4, H 2, H 2 O, H 2 S, and COS, wherein the gasifying agent carbon dioxide is collected from following steps; 2) cooling step: cooling the syngas using a primary heat exchanger and a secondary heat exchanger in sequence, wherein the primary heat exchanger employs carbon dioxide as a cooling medium whereby preheating the carbon dioxide as the gasifying agent in 1), and the secondary heat exchanger employs water as a cooling medium whereby producing vapor; 3) scrubbing step: introduced cooled syngas in 2) to a cyclone separator and a gas scrubber for dust removal and purification; 4) shift reaction: allowing purified syngas in 3) to react with the vapor so that part of carbon monoxide of the syngas is transformed into hydrogen and carbon dioxide, whereby modifying a ratio of hydrogen to carbon monoxide of the syngas; 5) desulfurizing step: desulfurizing modified syngas to remove H 2 S and COS therein; 6) decarburizing step: decarburizing desulfurized syngas to separate carbon dioxide therein; 7) catalytic synthesis: introducing desulfurized and decarburized syngas to a synthesizing tower where the desulfurized and desulfurized syngas is catalyzed to yield oil products and exhaust gas comprising carbon dioxide; 8) decarburizing of exhaust gas: decarburizing the exhaust gas comprising carbon dioxide and separating the carbon dioxide, and discharging effluent gas free of carbon dioxide; and 9) cycle of gasifying agent: introducing the carbon dioxide separated in 6) and 8) to the primary heat exchanger as the cooling medium in 2) whereby preheating the carbon dioxide, and transporting the preheated carbon dioxide to 1) as the gasifying agent for gasification.