A combustion head of a biomass combustion machine comprises a main groove box, a feeding port is formed in the main groove box, a plurality of igniter ports and air supply ports are formed in the maingroove box, a plurality of auxiliary groove boxes and a linkage device are arranged in the main groove box, the linkage device can drive the auxiliary groove boxes to stretch out and draw back in themain groove box, and ventilation nets are arranged on the main groove box and the auxiliary groove boxes. The linkage device is of a multi-connecting-rod combined structure, and all the connecting rods are connected end to end. The auxiliary groove box can stretch out and draw back in the main groove box, so that the combustion area of the combustion head is enlarged, the contact area of biomassfuel and air is increased, and the combustion efficiency is improved; the problem that in the prior art, the combustion area of a combustion head is too small under the condition that the size of a furnace opening of a tea drying oven is fixed is solved. And meanwhile, air is guaranteed to vertically move upwards through the ventilation net, so that the flame burns upwards.