The invention discloses a power distribution line reactive power optimization control method based on dynamic adjustment of a power factor interval and aims at solving the technical problem of realizing reactive power optimization control. The power distribution line reactive power optimization control method comprises the following steps: the data of a power distribution line and the parameters of elements are collected, the compensating capacity contributed by each reactive power compensating device is obtained, a master stations obtains the real-time load data of each power distribution transformer of the power distribution line and the compensating capacity of each reactive power compensation point, the master station calculates the optimal power factor value of each reactive power compensation point, the optimal power factor value, serving as a central point, is added with and subtracted from an expansion value, respectively, so that the power factor interval can be formed, the intelligent capacitor of each reactive power compensation point compares a real-time power factor value with the power factor interval and then the width of the power factor interval can be dynamically adjusted. Compared with the prior art, the power distribution line reactive power optimization control method based on dynamic adjustment of the power factor interval has the advantages that the width of the power factor interval can be adjusted dynamically, and the dynamic adjustment of the power factor interval is taken as a switching criterion to trigger switching control on each reactive power compensating device, and therefore, reactive power optimization control can be realized.