The virtual synchronous generator (VSG) provides a promising way to increase the inertia of inverter-based microgrids. However, when multiple VSGs are parallel in the grid, severe oscillations may be incurred. To address this problem, this article proposes a secondary frequency control for distributed VSGs with low bandwidth communication. The control can damp the oscillations and restore the frequency to the rated value without changing the virtual inertia provided by the VSGs. In addition, the proportional active power sharing is achieved by event-triggered communication mechanism, thereby reducing the communication burden considerably. The stability and Zeno-free behavior of the proposed control strategy are demonstrated by the ultimately uniformly bounded (UUB) theory. Simulations are conducted to verify the effectiveness of the proposed control strategy on the PSCAD/EMTDC platform.