Petroleum drilling rig derrick

The utility model relates to a petroleum drilling rig derrick, which is a design for improving the petroleum drilling rig derrick. The utility model comprises a derrick body that is integrally raised or put down by a Y-shaped bracket. The utility model is characterized in that neither leg of the derrick body is supported on the Y-shaped bracket under standing condition, and the four legs of the derrick body are in the state of four-leg grounding support. The petroleum drilling rig derrick of being integrally raised or put down and four-leg grounding support has the advantages of good integral stability and strong anti-torsion rigidity, and the derrick does not swing when lifting large load. After the four legs conduct grounding support, the derrick is strong in bearing capacity, and the difference of bearing capacity between the two front legs and the two rear legs is small.