Rotary drilling rig and main hoist hydraulic system thereof

The utility model provides a rotary drilling rig and a main hoist hydraulic system thereof, wherein the main hoist hydraulic system comprises a main valve, a main hoist motor, a first main pump and a second main pump, the first and the second main pumps supply oil for the main hoist motor through the main valve, and the main hoist hydraulic system further comprises a change valve which is used to communicate negative feedback mouths of the first and the second main pumps when a main hoist runs. The rotary drilling rig and the main hoist hydraulic system thereof can improve running speed of the main hoist.