The utility model relates to a mobile biomass fuel forming unit, which belongs the technical field of agricultural machinery. The unit comprises a biomass forming machine, a reduction box, a grinder and a feeding pipeline. The mobile biomass fuel forming unit is integrated on a movable compartment dragged by a tractor; a power output shaft of the tractor is in driving connection with an input shaft of the reduction box via a cardan joint; the output shaft of the reduction box is driven by a belt to be in driving connection with a power input shaft of the biomass forming machine; and the grinder is in driving connection with the power output shaft of the biomass forming machine by the belt. When the mobile biomass fuel forming unit works, the biomass fuel forming unit can be moved to the proper position on the farm or in the field as required by the tractor, tractor power can be directly used as the power of the mobile biomass fuel forming unit, and the effect of killing two birds with one stone can be achieved.