Products from pyrolysis of wood-based composites contain lots of valuable chemicals. The nitrogen compounds make such pyrolysis products different from those of general biomass. In this study, we characterized pyrolysis liquids and solid residues of waste wood-based composites such as particle board (PB) and medium density fiberboard (MDF). The study focuses mainly on the evolution of nitrogen compounds. Thermogravimetric analysis helped us to determine the optimum pyrolysis temperature. FTIR analysis was used to observe functions of nitrogen compounds in the solid residues. Components of pyrolysis liquids were analyzed by gas chromatography mass spectroscopy (GC-MS). Changes of FTIR spectrum indicate that C-N groups are reduced during pyrolysis process. Results from GC-MS analysis show that pyrolysis liquids are influenced a lot by the nitrogen compounds transferred from urea formaldehyde. Such changes will guide the utilization of pyrolysis products from waste wood-based composites.