A rotary shaft apparatus for a foldable electronic device, comprising a base plate, comprising a first supporting plane, and a rotary shaft assembly, the rotary shaft assembly comprises a first transmission assembly, comprising a main body and a fixing member detachably connected to the main body; the main body is rotatably connected to the base plate around a first axial direction; and the main body comprises a first supporting surface and a second supporting surface, and a second preset included angle is between the second supporting surface and the first supporting surface; a first supporting member, comprising a second supporting plane, and the first supporting member is rotatably connected to the fixing member around a second axial direction parallel to the first axial direction; a second transmission assembly, rotatably connected to the base plate around a third axial direction parallel to the first axial direction, and is movably connected to at least one of the first transmission assembly and the first supporting member; wherein, the rotary shaft apparatus has an unfolded state and a folded state; in the unfolded state, the second supporting plane, the first supporting surface and the first supporting plane are on the same plane; and in the folded state, a first preset included angle is between the second supporting plane and the first supporting plane, and the first supporting member and the base plate define a screen-accommodating space, and the second supporting surface abuts against the first supporting member; wherein, a side wall, close to the main body, of the fixing member is provided with a first cambered groove, and the first supporting member is provided with a first cambered structure; an accommodating space is defined by the fixing member and the main body, the first cambered structure is in sliding fit with the first cambered groove in the accommodating space. a base plate, comprising a first supporting plane, and a rotary shaft assembly, the rotary shaft assembly comprises a first transmission assembly, comprising a main body and a fixing member detachably connected to the main body; the main body is rotatably connected to the base plate around a first axial direction; and the main body comprises a first supporting surface and a second supporting surface, and a second preset included angle is between the second supporting surface and the first supporting surface; a first supporting member, comprising a second supporting plane, and the first supporting member is rotatably connected to the fixing member around a second axial direction parallel to the first axial direction; a second transmission assembly, rotatably connected to the base plate around a third axial direction parallel to the first axial direction, and is movably connected to at least one of the first transmission assembly and the first supporting member; a first transmission assembly, comprising a main body and a fixing member detachably connected to the main body; the main body is rotatably connected to the base plate around a first axial direction; and the main body comprises a first supporting surface and a second supporting surface, and a second preset included angle is between the second supporting surface and the first supporting surface; a first supporting member, comprising a second supporting plane, and the first supporting member is rotatably connected to the fixing member around a second axial direction parallel to the first axial direction; a second transmission assembly, rotatably connected to the base plate around a third axial direction parallel to the first axial direction, and is movably connected to at least one of the first transmission assembly and the first supporting member; wherein, the rotary shaft apparatus has an unfolded state and a folded state; in the unfolded state, the second supporting plane, the first supporting surface and the first supporting plane are on the same plane; and in the folded state, a first preset included angle is between the second supporting plane and the first supporting plane, and the first supporting member and the base plate define a screen-accommodating space, and the second supporting surface abuts against the first supporting member; wherein, a side wall, close to the main body, of the fixing member is provided with a first cambered groove, and the first supporting member is provided with a first cambered structure; an accommodating space is defined by the fixing member and the main body, the first cambered structure is in sliding fit with the first cambered groove in the accommodating space.