The rotary drilling rig is equipped with a circulation system in order to carry the rock cuttings broken by the drill bit at the bottom of the well to the ground in time for further drilling, and to cool the drill bit to protect the well wall and prevent drilling accidents such as well collapse and leakage. The circulating system includes drilling pump, ground manifold, mud tank, mud purification equipment, etc. the ground manifold includes high-pressure manifold, riser and water hose. The mud purification equipment includes vibrating screen, desander, desilter, centrifuge, etc.