Negative feedback hydraulic system and rotary drilling rig

The utility model discloses a negative feedback hydraulic system and a rotary drilling rig. The negative feedback hydraulic system comprises a first main pump, a second main pump, a first main valve, a second main valve, an overflow valve, an execution mechanism, a pivot handle valve and a pilot pump and also comprises a switch valve and a hydraulic control reversing valve; an oil discharging hole of the pilot pump is connected with a hydraulic control end of the hydraulic control reversing valve through the switch valve; the hydraulic control reversing valve is arranged on an oil circuit formed between the pivot handle valve and the second main valve; the hydraulic control reversing valve comprises two working states, wherein a first working oil opening and a second working oil opening of the pilot handle valve are communicated with a first hydraulic control end and a second hydraulic control end of the second main valve through the hydraulic control reversing valve respectively under the first working state and the oil circuit formed between the pivot handle valve and the second main valve is opened through the hydraulic control reversing valve and the oil pressure at the first hydraulic control end of the second main valve is equal to the oil pressure at the second hydraulic control end of the second main valve under the second working state. According to the negative feedback hydraulic system, the system energy loss is low under the abnormal working condition and the working reliability is high.