The utility model discloses a positioning device of a rock loader bucket, and belongs to the field of mine loading mechanical equipment. The positioning device is characterized by comprising a ratchet mounting base, a ratchet rotating shaft, a ratchet, a positioning ratchet, a bucket driving wheel, a bucket driving wheel rotating shaft, a bearing seat, a positioning electromagnet, a release spring, a machine body release spring mounting base, a ratchet release spring mounting base, a ratchet electromagnet contact plate and a positioning electromagnet magnetic core. The rotation position of the bucket driving wheel rotating shaft is locked through the ratchet and the positioning ratchet, and the position of the bucket driving wheel is further driven to be locked, so that a positioning part realizes a positioning function. The ratchet electromagnet contact plate is controlled by the positioning electromagnet magnetic core arranged in the positioning electromagnet to rotate along the ratchet rotating shaft so as to drive the ratchet to rotate, and then ratchet is correspondingly clamped in a tooth space of the positioning ratchet, so that a control part achieves the purpose of positioning the rock loader bucket. The positioning device of the rock loader bucket, disclosed by the utility model, is reasonable in product design structure, simple to operate, durable in use and convenient to popularize in industries.