An ion optical device includes one or more pairs of confinement electrode units arranged at two sides of a first direction; a power supply device for applying opposite radio-frequency voltages to the paired confinement electrode units respectively and forming thereon DC potentials distributed in a second direction orthogonal to the first direction to form a potential barrier herein over a length portion of the first direction; one first area and one second area positioned at two sides of the potential barrier in the second direction; and a control device connected with the power supply device for controlling an output thereof to change the potential barrier to manipulate the ions transported/stored in the first area being transferred to the second area through the potential barrier in ways based on the mass to charge ratio or mobility of the ions and continue being transported along the first direction.