The cable-stayed bridge is an indeterminate structure with high degrees, in the construction process of cable replacement, coordinate changes of any node of the bridge girder would give rise to the re-distribution of internal forces in the structure, while monitoring of cable force plays a critical role in the control of internal forces and alignment for the bridge. In order to simulate the bridge's state before cable replacement and analyze the changes of cable force, displacement and stress during the process of cable replacement, The author established a Spatial member system model of the G325 Jiujiang Bridge using Midas/Civil. During the monitoring process, frequency method was used in the measurement of cable force, and then the internal forces and alignment of the bridge was adjusted by controlling cable force .At last, the cable force and displacement of the bridge is basically returned pre-condition.