Abstract: Two biofilters,RA which had been exposed to varying concentration of ethyl acet ate for 20 days and RB which had been exposed to varying concentration of toluen e for 20 days, were used to remove mixed gas of ethyl acetate and toluene. The t wo biofilters used a mixture of compost and lava, with the initial medium moisture content of 50%. The experimental results demonstrated several characteristics of the two biofilters:The maximum elimination capacities were about 400g·m ^-3 ·h ^-1 for ethyl acetate and 50 g·m ^-3 ·h ^-1 for toluene;U nder the condition that the empty bed residence time was 1.0 minute, for e thyl a cetate concentration in the inlet air ranging from 2000 mg·m ^-3 to 4500m g·m ^-3 and toluene concentration ranging from 200mg·m ^-3 to 400m g·m ^-3 ,the removal efficiency for binary VOCs of both biofilter RA was ab ove 90%;Biofilter RA was better than biofilter RB in elimination capacity, stabi lity and adaptability.