In order to make the dynamic equivalent method for hydropower generator group based on phasor measurement information more suitable for the actual grid. A index use tie-line power oscillation to evaluate disturbance intensity is presented .Based on this index, consider disturbance location and it’s distance to the equivalent area, a disturbance selection method is proposed. Based on the equivalent method, dynamic equivalent online identification system is developed. The disturbance selection method proposed is verified using PMU measured disturbances data of Sichuan power grid China. Introduction Along with the increase of phasor measurement device(PMU) in the real power system, dynamic equivalent for hydropower generator group based on phasor measurement information has a broad application prospect. Dynamic equivalence is one of the most traditional research direction of power system, a large amount of research on the system dynamic equivalent model and parameter identification method are studied by many scholars and achieved abundant research results. But there is a little research on the application problem of equivalent in real power system . Reference 1-2 used 39 bus system with 10 generators to verify equivalent method the paper proposed; reference 3 did research on the equivalent method application in Tianjin power grid China, but disturbance selection is not involved . Existing literatures verify their equivalent method in simulation software generally. There is little Reference studies the application of equivalent method and disturbance selection in actual power grid, which affect the application of the equivalent method and the accuracy of equivalent. Therefore, this paper researches on dynamic equivalent for hydropower generator group based on phasor measurement information of tie-line. A index use tie-line power oscillation to evaluate disturbance intensity is presented, based on this index, consider disturbance location and it’s distance to the equivalent area, a disturbance selection method is proposed. And dynamic equivalent modeling software is developed. The equivalent method and disturbance selection method proposed is verified using PMU measured disturbances data of Sichuan power grid . Example analysis shows that disturbance data selection and dynamic equivalent method are effective and feasible. The method can make hydropower generator group dynamic characteristics simulation more accurate. Review of the dynamic equivalent method According to reference 4, the basic dynamic equivalent method for hydropower generator group based on phasor measurement information proposed in this paper can be concluded as follows: 6th International Conference on Machinery, Materials, Environment, Biotechnology and Computer (MMEBC 2016) © 2016. The authors Published by Atlantis Press 2192