A barbecue grill assembly includes a first bowl, a second bowl disposed on the first bowl, a grate disposed on the second bowl, a bolt and a crank. The first bowl has a first bottom and a first skirt, a central tube extending from the first bottom thereof and two first slots are defined in a periphery of the central tube and each disposed diametrically opposite in the central tube, a second slot is defined in the first skirt. The second bowl has a second bottom and a second skirt, the second bottom for charcoal disposed thereon has a central hole and a plurality of vents defined therein and a long tube has a first end having a receiving hole defined therein for a stud extending downwardly from the grate inserted therein and a second end inserted in the central tube, the second end of the long tube has a U-shaped tunnel defined therein such that the bolt extends through the second slot, the first slots and the U-shaped tunnel to engage to a nut. The crank is engaged between two engaging holes defined in the first skirt and is disposed between the bolt and the first bottom of the first bowl such that a distance from the second bottom of the second bowl to the grate is adjusted by rotating the crank.