Hydraulic system of hoisting mechanism and crane

The utility model discloses a hydraulic system of a hoisting mechanism, comprising an oil tank, a main pump, a main valve and a hydraulic motor, wherein an oil inlet and an oil outlet of the main pump are respectively connected with oil inlets of the oil tank and the main valve, an oil return port of the main valve is connected with the oil tank, and a first working oil port and a second working oil port of the main valve are respectively connected with a first cavity and a second cavity of the hydraulic motor; the hydraulic system also comprises an oil replenishing pump, a backpressure valve and a direction control valve; the backpressure valve is connected to an oil return pipe, so that back pressure is generated between the backpressure valve and the main valve; an oil inlet of the oil replenishing pump is communicated with the oil tank, and an oil outlet of the oil replenishing pump is communicated with an oil inlet of the direction control valve; and the oil inlet of the direction control valve is communicated with a pipeline between the backpressure valve and the main valve, the oil outlet of the direction control valve is communicated with the pipeline between the second working oil port of the main valve and the second cavity of the hydraulic motor, so that oil is enabled to flow to the second cavity of the hydraulic motor from the oil replenishing pump and/or the oil return pipe. The utility model also discloses a crane. The hydraulic system prevents the hydraulic motor from sucking air due to system leakage and avoids the hook gliding situation of the hoisting mechanism.