As biomass materials, poplar processing residues could be convertedtoethanolorbiohydrogen(Gonza ́lez-Garcı ́aetal.,2010;Cui et al., 2010). However, this method is not economical, mainly due to the high cost of the hydrolysis process and the low yield (Sun and Cheng, 2002). A new alternative is to convert poplar processing residues to biogas by anaerobic digestion. Anaerobic digestion has been widely accepted for great interest from the view of environmental and renewable energy through treatment and recycling of biomass wastes (Amon et al., 2007