The invention relates to an underwater cable connector. An insertion head part is installed in an oil tube suspender, a piston A is arranged in an insertion head chamber in the oil tube suspender, the axle center of the piston A is sleeved on an insertion head conducting ring, two ends of the insertion head conducting ring are respectively provided with insertion head non-conductive parts, a spring A is sleeved at the periphery of a rear insertion head non-conductive part, and a cable A is connected with the insertion head conducting ring; a socket part is fixed on an underwater Christmas tree body and in a socket chamber of a socket shell, a socket body is sleeved in an internal guiding sleeve of the socket shell, a guiding column is arranged at the axle center of the socket body, and a socket conducting ring is arranged on the contact surface of the guiding column and the socket body; a spring B is arranged in a spring chamber of the socket body, and the bottom of the spring chamber is connected with a hydraulic pressure compensated cavity; a compensation liquid flow channel is additionally formed in the socket body; the socket conducting ring is connected with outside by the cable B; and the inner cavity of the compensated cavity shell is sequentially provided with the hydraulic pressure compensated cavity, and the piston B and a second spring chamber. The device realizes the underwater reliable insertion and pulling connection.