The system defines an assembly formed by a truck (1) with a compacting box (2) of wastes and handling crane (3) of a receptor container (4) and containing the wastes assigned to be compacted. The compacting box includes driving hydraulic means (6) of the loading and unloading doors (5), as well as safety means in the lock of the unloading door on which the compacting is carried out by means of pushing the wastes by a vertical and displaceable wall (9) in the inside of the compacting box. The crane includes hooking means (12) of the container in order to place this one facing the loading door (7) of the compacting box, as well as driving means (15) of a mechanism (16) to produce the opening of the corresponding unloading gates (17) foreseen to such effect in the container itself.