Abstract: In order to investigate the efficiency of excavation and load and transportation of the existing municipal solid waste (MSW) from the landfill, and the influence of direct co-incineration of existing MSW on the working condition of an MSW incineration plant, a pilot-scale study was conducted on the landfill adjacent to the MSW incineration plant in southern China. The results showed that the essential component of the existing MSW in the whole landfill was about 56% of rubber-plastic, and its lower heating value was 5037 kJ/kg in the wet base. The age of the existing MSW in the pilot-scale area was 4 to 8 years and the efficiency of excavation, load and transportation of the existing MSW could reach 141 t/h. At the co-incineration ratio of 50%, the incineration amount was increased by 22% and reached 104% of the designed value, to maintain the furnace’s thermal load. At the same time, the generation ratios of fly ash and slag were all increased by 38%, and the standardized emission of flue gas pollutants as well as the treatment and utilization of fly ash and slag were not affected. It was still not necessary to increase the volume of the secondary air or introduce assist incineration to maintain the sufficient incineration of MSW. For the treatment of flue gas, it was not necessary to enable the process of dry deacidification but the denitrification load was significantly increased. Consumption of slaked lime and liquid ammonia was increased by 41% and 194%, respectively. The emission concentrations of dioxin were 0.062 and 0.034 ng-TEQ/m³ of toxicity equivalency quantity, which can be further decreased.