The utility model belongs to the technical field of oil and natural gas mines the well drilling, specifically provide a big moment of torsion back -off table drive device is adorned to well drilling sled, including transmission support (9), hydraulic motor (1), shaft coupling (2), gearbox (3), cardan shaft (4), carousel (5) and brake assembly (6), hydraulic motor (1), gearbox and brake assembly (6) all are fixed in on transmission support (9), wherein, gearbox (3) is connected through shaft coupling (2) in hydraulic motor (1), and carousel (5) is connected through cardan shaft (4) in gearbox (3), brake assembly (6) are connected with gearbox (3). The utility model discloses a modularization skid - mounted structure, its process manipulate safe and reliable, and on -the -spot installation and dismantle fast, convenient can provide conventional carousel or top and drive the big torque value (being greater than 55000N. M) that can not provide and be used for handling well drilling technical failure in the pit.