To improve the steady state performance of the grid-side converter of the flywheel energy storage array system (FESAS) in charge-discharge mode, reduce the harmonic content of the three-phase current on the grid side and accelerate the dynamic response of the system, taking three-phase two-level voltage type converter as the research object, an improved direct power control strategy for grid-side converter based on model predictive algorithm was proposed. Firstly, the grid-side power prediction model was established. And then the corresponding AC-side reference output voltage was calculated according to the above prediction model so that the power deviation in the next sampling period is zero. The switching signal was generated by the space vector pulse width modulation module to control the grid-side converter. In addition, the strategy adopted the outer loop structure of the square of the DC bus voltage, and the control goal was to quickly stabilize the DC bus voltage. Finally, the proposed control strategy was verified on the PSCAD/EMTDC simulation platform, and the results show that, compared with the traditional direct power control strategy, the proposed control strategy not only has superior steady state performance, power quality is consistent with the expected, but also has fast dynamic response.