According to load characteristics of the port crane, through the analysis of lifting control principle and the state equation of the motor, the motor drag test system had been established base on PLC and inverter, the simulation and experimental analysis of the model were carried out by the control strategy of the transfer frequency control. It was verified that the VVVF control system had large energy saving space, especially for full load and heavy load control, which provides a theoretical and experimental basis for the energy saving of port cranes.