Robot joint structure

The invention discloses a robot joint structure. The robot joint structure comprises a first flange; the second flange is rotationally connected with the first flange; in an initial state, the length of a first cable between the first flange and the second flange and the length of a second cable between the first flange and the second flange are first lengths; when the first flange and the second flange relatively rotate by a preset angle, the length of the first cable between the first flange and the second flange is a second length, and the length of the second cable between the first flange and the second flange is a third length; the adjusting mechanism is used for enabling the difference value between the second length and the first length to be larger than or equal to the difference value between the first length and the third length. According to the invention, the phenomenon that the driving cable is loosened when the joint flange rotates can be completely eliminated or compensated, so that the postur