To examine the frequency requirement of a power grid, the coordination strategy of oscillation suppression and fast frequency modulation of a high hydropower proportion isolated network is studied. First, the frequency modulation priority index of a hydropower unit is defined and the frequency modulation priority of the unit is established. Secondly, based on the priority index of frequency modulation, the selection method of non-frequency modulation hydropower units is proposed, and the frequency modulation control strategy of frequency modulation units is determined. Then the calculation method of an emergency control delay is put forward and the correction formula of a frequency amplification factor is defined. Finally, an actual example is given to verify the effectiveness of the proposed strategy, and the effect of adjusting the emergency control delay factor and the frequency amplification factor is examined. The problem of coordinating the fast frequency modulation and reducing the oscillation of an isolated network is solved without parameter resetting. This can be used as a reference for the frequency control of a high hydropower proportion isolated network. This work is supported by the Major Special Science and Technology Projects of China Southern Power Grid (No. 036000KK52180012).