A sheet medium processing device comprises a housing, a feeding mechanism (1) mounted on the housing, a stacking mechanism (2) and a switching mechanism (3). The stacking mechanism (2), which is located downstream of the feeding mechanism (1), comprises an upper channel (20), a lower channel (21) and a channel driving mechanism (22). The lower channel is fixedly connected with the housing, and the upper channel is hinged with the housing with one end thereof separatable from or contactable with the lower channel. The channel driving mechanism is used to drive the upper and lower channels to move synchronously to transport sheet mediums. The switching mechanism (3) comprises a first cam (30) and a cam driving mechanism (31), wherein the cam is joined with the upper channel to drive the upper channel to rotate. Different transporting directions are formed by adjusting the position relationship between the upper channel and the lower channel of the stacking mechanism using the switching mechanism and thus sheet mediums are transported to different destinations according to specific requirements.