The invention provides a telescopic rotary joint. The joint comprises a cutter plate, a shield housing, an excavating chamber, a rotary joint, a driving device and a front shield separating plate, therotary joint comprises a rotary joint rotor and a rotary joint stator, a copper sleeve is fixed to the rotary joint rotor, one end of a stirring shaft penetrates through the copper sleeve to be fixedly connected with a stirring bar, the other end of the stirring shaft is fixedly connected with a motor through a coupler, the rotary joint stator is fixedly provided with the driving device, the driving device is fixedly provided with a rotary joint fixing frame, the rotary joint fixing frame is fixedly provided with a hydraulic oil cylinder, the hydraulic oil cylinder is fixedly connected with amotor installing frame, and the motor is fixed to the interior of the motor installing frame. The length of the stirring bar is adjustable, adjustment can be conducted according to different geologies to reduce the risks of stirring damage and the wearing of the sealing pressing ring of the driving device, and the geological adaptability and safety of a shield machine are improved.