To identify the tension of in-service cable expediently and accurately, a cable tension identification method based on static testing measures is proposed by taking cable stress stiffening effect and principle of static equilibrium into account. According to the analysis on the process of cable tension identification and the key technique, a new compound clamp type with the soft metal lining is proposed. The rule of the contact distortion evolvement between the clamp and the cable is analyzed by dynamic nonlinear explicit analysis method, and the law of the friction change following the clamping force is studied. Thus, the reasonability and feasibility of this method is theoretically illuminated. The identified tension only depends on the displacement of load application point and the load force. The proposed method avoids the drawback of normal cable measuring methods where the measuring accuracy is greatly affected by cable boundary conditions and values of material parameters. The tension measured in the method is only related to the displacement of force point and the value of force. Therefore, it provides a new idea for cable tension identification of flexible cable.