Counterweight assembly, operation machine main machine platform assembly and operation machine

The utility model provides a counterweight assembly, an operation machine host platform assembly and an operation machine. The counterweight assembly comprises a counterweight group which is rotatably connected to a host platform of the operation machine; one end of the connecting rod group is rotationally connected to the host platform, and the other end is rotationally connected to the counterweight group; one end of the driving part is rotationally connected to the host platform, and the other end is rotationally connected to the connecting rod group; and the connecting rod group can drive the counterweight group to rotate relative to the host platform under the driving of the driving piece. During actual operation, the position of the counterweight group needs to be adjusted according to different required hoisting capacities so as to meet different requirements. The connecting rod group is driven by the driving part, so that the connecting rod group can drive the counterweight group to rotate relative to