For the odour from fermentation processing of municipal solid waste biological mechanical treatment, a compost biofilter was established to investigate its performance and the characteristics change of compost. The component and TVOC concentration in odors, removal efficiency of biofilter, and total carbon (TC), total nitrogen (TN), total phosphorus (TP), organic matter (OM), pH value and bacterial colony in compost media were measured respectively. SPME-GC-MS analysis showed that the main components of odors were BTEX, terpenes and alkane. The range of TVOC concentrations in odors during a fermentation process period and removal efficiencies of biofilter were 68.3 x 10(-6) -3.3 x 10(-6) (volume fraction), 31.5%-84.8% respectively. After about 4 months operation, TN, TC, TP and OM in compost were kept almost stably, but the dissolved N experienced an increase of 53.7%, and the dissolved P decreased 19.6%. The pH value experienced an increase in the former period and kept stable finally at about 7.8, which excursion was from 7.49 to 7.86. Analytical results for bacterial colony in packing material indicated that bacteria and mould colony counts increased, but yeasts and actinomyces decreased along with biofilter operation, which were 3.1, 3.4, 0.04, 0.07 times of their initial values respectively.