Lifting system of crane

The invention discloses a lifting system of a crane, which is used for lifting or descending a lifted object with two lifting points. The lifting system comprises a first transmission mechanism and a second transmission mechanism. The first transmission mechanism and the second transmission mechanism are in transmission connection through a synchronizer and have the same structures. Each transmission mechanism comprises a motor, a tipping motor, a winding drum and a planetary reducer, wherein the motor and the tipping motor are respectively in transmission connection with the planetary reducer and respectively transmit power to the planetary reducer; the planetary reducer is in transmission connection with the winding drum and transmits the power to the winding drum; the winding drum is provided with a rope; and one end of the rope is fixed to the winding drum and the other end of the rope is connected to one lifting point of the lifted object. According to the lifting system, after one set of transmission mechanism is braked, the other set of transmission mechanism can continuously output the rotating speed to realize the tipping action of the lifted object; meanwhile, the safetyis improved and the service life of a transmission system is prolonged.