Recently, landfill gas (LFG) has attracted considerable interest as a source of regenerative energy for the production of heat and power. In the present study, the characteristics of flame blowout limits for landfill gas-liquified propane gas (LFG-LPG) mixed fuels in a swirling nonpremixed combustor were investigated. Validations of existing blowout models were conducted, and global parameters were suggested to explain the characteristics of the blowout limit for LFG-LPG mixed fuels in swirling nonpremixed flames. It was found that the flame stability of LFG-LPG mixed fuels was lower than that of CH4 under weak swirl conditions. Under strong swirl conditions, however, LFG-LPG mixed fuels had a similar or larger stable flame region with an increase of the air flow rate compared to those of CH4. Blowout velocities estimated by the Kalghatgi model as well as the Dahm-Mayman model, in simple jet flames and nonswirling flames with a coaxial air flow, respectively, were in good agreement with measurements from CH4-CO2 mixed fuels. For LFG-LPG mixed fuels, however, these models presented highly inaccurate estimations. Finally, it was identified that the flame blowouts of LFG-LPG mixed fuels were affected mainly by the CO2 ratio and stoichiometric air-fuel ratio of the fuels under weak swirl conditions and by the higher heating value of the fuels under strong swirl conditions. From these results, new global parameters, CO2(%)/(A/F)(st), under weak swirl condition and higher-heating value under strong swirl condition, were suggested to characterize the flame blowout velocity of LFG-LPG mixed fuels.