Rotary control valve unit, rotary control hydraulic system and crane

The invention discloses a rotary control valve unit, a rotary control hydraulic system and a crane. The rotary control valve unit comprises a proportional reversing valve, a shuttle valve and a fixed-difference overflow valve, wherein two oil inlets of the shuttle valve are respectively communicated with two working oil ports of the proportional reversing valve, oil outlets of the shuttle valve are communicated with a second pressure sensing port of the fixed-difference overflow valve, a first pressure sensing port of the fixed-difference overflow valve is communicated with oil inlets of the proportional reversing valve, and overflow oil ports are communicated with an oil return path. Under the loading state, the two pressure sensing ports of the fixed-difference overflow valve sense the pressure of the oil inlets and the high-pressure working oil ports of the proportional reversing valve, when the difference of the two pressures is larger than a preset value, the overflow pressure of the fixed-difference overflow valve is correspondingly adjusted, part hydraulic oil of a high-pressure oil source enters the oil return path for decompression through the overflow oil ports of the fixed-difference overflow valve so as to stabilize the difference of oil pressure of the oil inlets and load pressure of the proportional reversing valve, accordingly the influence on flow of the high-pressure working oil ports caused by load pressure changing is reduced, and load flow stability is improved.