The invention discloses a method for producing and heating a carbon-containing fuel gasifying agent and a device thereof, belonging to the gasification field of fuels containing carbon. Parts of syngas generated by a gasifier is combusted through chemical-looping combustion and the heat generated therefrom is recovered in a heat exchanger network, and under the condition that external H2O and/or CO2 are added, the mixed gas of H2O and CO2 with enough high temperature and as large as possible flow is obtained and used as the gasifying agent. When the gas agent is lack of heat and the conversion rate is low, O2 is transferred to the gasifying agent from the O2-containing gas through a peroxy-separator. The gasifying agent obtained by the method is sent to a ground gasifier or an underground gasifier to react with the fuels containing the carbon, and the syngas containing no N2 is obtained. By adjusting the composition of the gasifying agent, the composition of the syngas can be adjusted flexibly according to downstream requirements. The discharge of CO2 is low during the whole gasification process. The method relies little on environment and after a gasification system starts working normally, the syngas can be obtained through the gasification of the fuels containing the carbon so as to provide energy for continuous production, and obtained intermediate material flow is favorable for doping the O2 into the gasifier.