In traditional VSG control, the introduction of the inertia moment and damping coefficient of the synchronous generator into the photovoltaic inverter will result in poor dynamic adjustment capabilities of the photovoltaic grid-connected system. In view of this problem, this study proposes an improved VSG control strategy. The relationship between power angle and active power and the transient process of the rotor angular frequency oscillation period are discussed through the mathematical model of the converter. The principles for selecting moment of inertia and damping coefficient are given, and the rate of change of moment of inertia and angular frequency as well as damping coefficient and angular frequency are analyzed. The relationship between the changes leads to the improvement strategy of photovoltaic grid-connected under the control of adaptive VSG. The simulation results show that the photovoltaic grid-connected system based on the adaptive VSG control strategy has a good dynamic response, which proves the effectiveness and superiority of the improved strategy.