Auxiliary boom control valve, auxiliary boom hydraulic control system and crane

The invention relates to an auxiliary boom control valve, an auxiliary boom hydraulic control system and a crane. The auxiliary boom control valve comprises a valve body, wherein a switching valve, a reversing valve and an oil-returning pressure control valve are arranged on the valve body; an oil opening of the switching valve is connected with an oil inlet in the valve body; the other oil opening of the switching valve is connected with an oil inlet of the reversing valve; the switching valve is used for controlling on and off of a main oil supply line; the reversing valve is used for reversing between at least two working oil openings in the valve body; one oil opening of the oil-returning pressure control valve is connected with an oil returning opening of the reversing valve; the other oil opening of the oil-returning pressure control valve is connected with the oil returning opening in the valve body; the oil-returning pressure control valve is used for controlling the magnitude of the oil returning backpressure; a spring-free control cavity of the oil-returning pressure control valve is connected with a connection oil line between the switching valve and the reversing valve. The auxiliary boom control valve is capable of reducing the oil returning backpressure during working and increasing the oil returning backpressure when not working, thereby avoiding the danger caused by rapid falling of a working cylinder when working again.