Virtual Synchronous Generator can emulate the characteristics of a synchronous generator to provide inertia and damping for microgrid systems. In the case of employing a T-type three-level converter structure, the traditional model predictive control method has a large computational burden, and it is difficult to determine the weighting factor of the midpoint voltage. Additionally, although fixed-parameter VSG control can provide inertia and damping, it cannot guarantee frequency regulation performance. To address these issues, this paper proposes an optimal switching sequence model predictive control strategy for T-type three-level VSG with parameter synergistically adaptive control method. This method analyses the impact of different vectors output by the T-type three-level inverter on the midpoint potential and the charging and discharging status of the DC-side capacitor. By setting constraint conditions, the switching sequence of the inverter is optimized, eliminating the weighting factor used to control the midpoint voltage in traditional cost functions, resulting in smaller fluctuations in the DC-side voltage. Based on the active closed-loop transfer function of VSG, the optimal damping ratio is set, and a parameter synergistically adaptive formula is designed to allow coordinated adjustment of VSG parameters, effectively improving microgrid frequency stability during power fluctuations.