Abstract: NOx formation behaviors of two kinds of RDF (Refuse Derived Fuel) samples with different N content were studied using a fluidized bed combustor. The results show that RDF samples are easily to be combusted in the fluidized bed reactor and the combustion process is stable without external energy. The distribution of NOx contents depends on the temperature distribution along the height of the fluidized bed. Under the same operation conditions, the higher nitrogen content in the RDF sample leads to higher NOx concentration in the flue gas. Both the extra air ratio and the injection of secondary air can affect the NOx formation characteristics, especially for the RDF with high nitrogen content.