A rotational positioning mechanism includes a base, a rotational shaft, a rotational plate, at least two first switches and a positioning assembly. The rotational shaft is pivoted to the base. The rotational plate is connected to the rotational shaft and is configured to rotate relative to the base along with the rotational shaft. The rotational plate has at least two first positioning portions. The two first switches are respectively disposed at the two first positioning portions. The positioning assembly is disposed at the base, and comprises a positioning component configured to form a structural interference with any one of the first positioning portions or remove the structural interference. After the positioning component forms the structural interference with any one of the first positioning portions, the positioning component abuts against the corresponding first switch, and the degree of rotational freedom of the rotational plate and the rotational shaft are restricted.