The invention provides a four-degree-of-freedom integrated robot joint mechanism, relates to a robot joint, and aims to solve the problems of complex and huge whole mechanism of the robot because the conventional actually applied robot basically consists of single-degree-of-freedom joints. The robot joint comprises the technical key points that: the inner surface of a driving cylinder of the joint mechanism is provided with dot matrix windings; the outer surface of the main body of a driven element is provided with dot matrix permanent magnets; three first end plates and three second end plates are combined together respectively to form contours, and all the contours are circular rings which are coaxial with the inner surface of the driving cylinder; the main bodies of three cylindrical curve driven elements are combined together to form contours, and the contours are cylinders which are coaxial with the inner surface of the driving cylinder; each driven element axially slides along two corresponding guide rods; and one end of each of the three connecting rods is connected with the extending end of an extending end rod of each of the three driven elements, while the other end is connected with the inner side surface of an end platform through a spherical pair. The mechanism can be applied to the fields of robot joints and rehabilitation of patients with joint injuries or dyskinesia and the like.