Voltage control of traditional virtual synchronous generator (VSG) employs a droop characteristic, which leads to steady-state voltage deviations. Moreover, due to the lack of voltage support from large power grids, parallel VSG systems in islanded microgrids are prone to voltage deviations or even exceeding limits when subjected to load disturbances. To address this issue, a bus voltage support control strategy for parallel VSGs in islanded microgrids based on adaptive voltage compensation is proposed. By introducing an additional voltage compensation control and an adaptive voltage compensation coefficient into the traditional VSG reactive power control loop, multiple VSGs can autonomously coordinate and cooperate in a fully decentralized manner without requiring extra measurement devices or communication links. The proposed control method improves the steady-state voltage control accuracy and effectively suppress bus voltage fluctuations caused by load disturbances. Furthermore, key control parameters are designed through stability analysis. Finally, the effectiveness of the proposed control method is verified through simulation and experiments.