A rotary shaft apparatus includes a base plate and a rotary shaft assembly; the rotary shaft assembly includes a first transmission assembly, a second transmission assembly and a first supporting member; the first transmission assembly is rotatably connected to the base plate around a first axial direction; the first supporting member is rotatably connected to the first transmission assembly around a second axial direction parallel to the first axial direction, and is movably connected to the second transmission assembly; the second transmission assembly is rotatably connected to the base plate around a third axial direction parallel to the first axial direction.