A furnace using biomass pellets as fuel, comprising a housing arranged on a base, wherein the housing is internally provided with a burning chamber, the bottom of which is provided with a burning grate, and the burning chamber is connected with a primary oxygen supply device; the primary oxygen supply device comprises an oxygen supply cylinder that communicates with the outside, and the bottom end of the oxygen supply cylinder is connected with an oxygen supply pipe II configured to blow air over the burning grate, and a plurality of air outlet holes I is defined in the oxygen supply cylinder.