A control method and a control system are provided. A valve closing position of a valve device can be controlled according to the current flow direction or working mode of a refrigerant. A stroke of the valve device from a fully-opened position to a fully-closed position is defined as a total valve closing stroke. When the flow direction of the refrigerant is a forward direction, the valve device is controlled to operate at a first valve closing position, and when the flow direction of the refrigerant is a reverse direction, the valve device is controlled to operate at a second valve closing position. The first valve closing position is different from the second valve closing position, such that wear caused by valve closing can be reduced.