For grid-forming energy storage integrated into power systems dominated by new energy，voltage drops in the grid are caused by the instability of new energy generation. Leading to transient power angle instability and overcurrent issues in grid-forming energy storage. A transient power angle stability control strategy based on power angle deviation feedback is proposed in the article. Firstly，grid-forming energy storage adopts virtual synchronous generator （VSG） control，and a corresponding model is established based on VSG control. Secondly，the relationship between active power，power angle stability, and output current is analyzed based on VSG power angle characteristics, and the causes of power angle instability are further analyzed using phase portrait theory. Based on this，an adaptive adjustment strategy for the power angle deviation feedback coefficient is designed，considering the power angle stability range and active power deviation. The active power deviation is controlled through power angle deviation feedback, thereby suppressing power angle amplification，maintaining power angle stability，and effectively mitigating overcurrent. Finally, time-domain simulations verify the correctness of the theoretical analysis and the effectiveness of the proposed control method.