The relation between cable tension and natural vibration frequencies needs to be defined accurately for measurement of cable tension by vibration method. It is necessary to express the geometric shape of supper long stay cable exactly and consider sag in order to meet the demand of measurement accuracy for super long-span cable-stayed bridge. The cable-vibration discrete model is established on the base of the catenary equation for static profile of stay cable developed by static analysis with the consideration of cable sag, inclination angle, self-weight and variation of cable tension along the cable. Transfer matrix method of multibody system is used to compute natural vibration frequencies of cable based on the discrete model. The relation between cable tension and natural vibration frequencies is described by solving characteristic equation. The measurement accuracy of super long stay cable tension is improved and the vibration method for measurement of cable tension is further perfected. The field measurementr esults are analyzed and it is indicated that the proposed method has high computational efficiency because of low order of system matrix and can effectively sat isfy the requirements for measurement accuracy of cable tension.