Under large disturbances in power grids, virtual synchronous generators (VSG) face a high risk of transient instability. Among them, power angle stability and frequency stability are two key factors for ensuring safe and stable VSG operation. However, existing studies seldom consider these two aspects in an integrated manner. To address this gap, a VSG large signal equivalent model is first established, and the influence of VSG control parameters on transient power angle stability and frequency stability under different fault depths is analyzed, revealing the inherent conflict between the two stability objectives. Subsequently, an adaptive transient control strategy based on angular frequency negative feedback is proposed. By introducing virtual inertia, virtual damping, and virtual power reshaping, this method enhances both rotor angle stability and frequency stability. To further optimize the transient performance, a control parameter design method that accounts for frequency dynamic response is proposed, along with a quantitative characterization of the feasible domain of parameters. Finally, the effectiveness of the proposed method and parameter design is verified through Simulink and RT-Lab hardware-in-the-loop (HIL) platform