The invention particularly relates to a biomass combustor, which belongs to the technical filed of energy conservation and emission reduction heat energy equipment and comprises a dual auger feeder, a feed drive system, a secondary oxygen supplement device and a combustion chamber, wherein the combustion chamber is connected with the dual auger feeder; the dual auger feeder is formed by two feed pipes and a connecting pipe; spiral material push rods are arranged in the feed pipes; an anti-backfire plate is arranged in the connecting pipe; a slag pushing and tar removing mechanism is arranged below the dual auger feeder; an air blowing and air distribution device and an automatic ignition device are arranged at the right lower part of the dual auger feeder; the secondary oxygen supplement device is arranged above the combustion chamber; the air blowing and air distribution device and the secondary oxygen supplement device are communicated with the combustion chamber respectively. According to the biomass combustor, backfiring is avoided, the safety is improved, automatic slag removing is realized, the problem that the fuels are easy to coke during combustion and further to be attached at the bottom of the combustion chamber is solved, normal combustion space and smooth ventilation of the combustion chamber are ensured, the combustion efficiency is improved, and the problem of smoking due to insufficient combustion of an ordinary combustor is solved.