A sheet alignment and ejection mechanism includes a sheet alignment device, a sheet ejection device, a power device and a transmission unit. The sheet alignment device includes a first one-way element. The sheet ejection device includes a second one-way element. The transmission unit includes plural gears. The transmission unit is connected with the power device, the first one-way element and the second one-way element for driving rotation of the first one-way element and the second one-way element. The first one-way element and the second one-way element are rotated in opposite directions. When the first one-way element is rotated in a first direction, the sheets aligned on a sheet placement tray are aligned by the sheet alignment device. When the second one-way element is rotated in the first direction, the stapled sheets are ejected out of the sheet placement tray by the sheet ejection device.