A rhizome-growth monitoring device of a clonal plate is provided, including a supporting frame. A first adjustment rack is fixed above a side of the supporting frame, a side end of which is movably connected to a second adjustment rack. A connection sleeve is movably connected to a bottom end of the second adjustment rack. A lifting cylinder is fixed in the connection sleeve. A camera group is fixed to the lifting cylinder through a connection plate. A rhizome growth monitoring sleeve is fixed at a bottom end of the connection plate, and includes an outer sleeve, an inner sleeve, and a radar monitoring head. The outer sleeve is fixed onto the bottom end of the connection plate. The inner sleeve is screwed to an inner side of the outer sleeve. The radar monitoring head is installed in the inner sleeve and close to a bottom surface thereof.