A cable head for petroleum logging includes a first connector and a second connector; there is a tension rod between the first connector and the second connector; a first piston, a second piston and a third piston are successively provided on the upper part, the middle part and the lower part of the first connector; the diameter of the second piston is greater than the diameters of the first and third piston respectively; the first and second piston are sealed and mounted inside a first cylinder; the third piston is sealed and mounted inside a second cylinder; the lower part of the second cylinder is fixedly connected with the second connector; a balance cavity is formed between the lower end face of the second piston and the upper end face of the second cylinder when the lower end face of the first cylinder is contacted with the upper end face of second cylinder; the balance cavity communicates with the external by a passage on the first or second cylinder; an axial projected area of the lower end face of the second piston is equal to a cross section area of the first piston. When the cable head is stuck in the well in use, the logging cable can be disconnected by breaking the tension rod, thus it is no need to overcome the pressure of fluid in the deep well.