The invention provides a cable-stayed bridge cable adjusting method and a cable adjusting system adopting the cable adjusting method. The cable-stayed bridge cable adjusting method includes the following steps that S1, after primary tensioning of inhaul cables and bridge deck system construction are completed, the inhaul cables of a bridge are divided into regions and numbered towards the two ends of the bridge with a cable tower as the center, the inhaul cables located at the two sides of the cable tower in the length direction of the bridge are arranged in each region, and the numbers of the inhaul cables at the two sides are equal; S2, an intelligent tensioning jack connected with a control center is mounted on each inhaul cable of the first region; S3, overall cable force adjustment is carried out on all the inhaul cables of the first region; S4, cable force of all the inhaul cables is finely adjusted according to displayed cable force of all the inhaul cables of the first region and designed target values, so that the cable force is made to reach a design goal; S5, the step S2, the step S3 and the step S4 are repeated, so that the inhaul cables of all the divided regions are sequentially adjusted until cable adjustment of the last region is completed; and S6, all the intelligent tensioning jacks are dismantled, and inhaul cable adjustment of the whole bridge is completed. The cable adjusting method and system are high in efficiency and reduce cost, and operation is convenient.