A child motion apparatus, characterized by comprising: an apparatus base; a movable carrier, comprising a platform and being movably disposed on the apparatus base along a sliding direction; a seat mount, rotatably connected to the platform about a rotation axis perpendicular to the sliding direction; a motion mechanism, comprising: a sliding mechanism, connecting the platform and the apparatus base for sliding the platform relative to the apparatus base along the sliding direction; and a rotating mechanism, disposed on the platform and connected to the seat mount for rotating the seat mount about the rotation axis; and a seat assembly, comprising a seat frame and a connection support fixedly connected to the seat frame, the connection support being detachably connected to the seat mount, wherein the seat mount comprises a first engagement structure of a first non-circular structure profile relative to the rotation axis; the connection support comprises a second engagement structure of a second non-circular structure profile; and the first non-circular structure profile matches with the second non-circular structure profile, characterized in that the connection support is detachably connected to the seat mount by engaging the second engagement structure with the first engagement structure in one of at least two orientations of the connection support relative to the seat mount. an apparatus base; a movable carrier, comprising a platform and being movably disposed on the apparatus base along a sliding direction; a seat mount, rotatably connected to the platform about a rotation axis perpendicular to the sliding direction; a motion mechanism, comprising: a sliding mechanism, connecting the platform and the apparatus base for sliding the platform relative to the apparatus base along the sliding direction; and a rotating mechanism, disposed on the platform and connected to the seat mount for rotating the seat mount about the rotation axis; and a seat assembly, comprising a seat frame and a connection support fixedly connected to the seat frame, the connection support being detachably connected to the seat mount, wherein the seat mount comprises a first engagement structure of a first non-circular structure profile relative to the rotation axis; the connection support comprises a second engagement structure of a second non-circular structure profile; and the first non-circular structure profile matches with the second non-circular structure profile, characterized in that the connection support is detachably connected to the seat mount by engaging the second engagement structure with the first engagement structure in one of at least two orientations of the connection support relative to the seat mount. a sliding mechanism, connecting the platform and the apparatus base for sliding the platform relative to the apparatus base along the sliding direction; and a rotating mechanism, disposed on the platform and connected to the seat mount for rotating the seat mount about the rotation axis; and a seat assembly, comprising a seat frame and a connection support fixedly connected to the seat frame, the connection support being detachably connected to the seat mount, wherein the seat mount comprises a first engagement structure of a first non-circular structure profile relative to the rotation axis; the connection support comprises a second engagement structure of a second non-circular structure profile; and the first non-circular structure profile matches with the second non-circular structure profile, characterized in that the connection support is detachably connected to the seat mount by engaging the second engagement structure with the first engagement structure in one of at least two orientations of the connection support relative to the seat mount.